U.S. patent application number 12/577333 was filed with the patent office on 2010-05-06 for aromatic-aliphatic polyester hot melt adhesives for roll-applied labels.
This patent application is currently assigned to Eastman Chemical Company. Invention is credited to Joshua Seth Cannon, Michael Eugene Donelson, Scott Ellery George, Gary Robert Robe, Marcus David Shelby, Candace Michele Tanner, Freddie Wayne Williams.
Application Number | 20100112251 12/577333 |
Document ID | / |
Family ID | 42131778 |
Filed Date | 2010-05-06 |
United States Patent
Application |
20100112251 |
Kind Code |
A1 |
Shelby; Marcus David ; et
al. |
May 6, 2010 |
AROMATIC-ALIPHATIC POLYESTER HOT MELT ADHESIVES FOR ROLL-APPLIED
LABELS
Abstract
Disclosed are hot-melt adhesives prepared from
aromatic-aliphatic polyesters containing terephthalic acid in
combination with adipic acid, glutaric acid, or a mixture thereof,
as diacid components and a diol component containing
1,4-butanediol, 1,6-hexanediol, or a combination thereof. These
adhesives set up rapidly within a well-defined temperature window.
The hot-melt adhesives can be used in a variety of applications,
but are especially suited as seaming adhesives for roll-applied
labels. These adhesives have melting temperatures and
crystallization properties that allow their application at
temperatures cool enough to prevent curling and premature shrinkage
of the shrink label during seaming, and yet produce strong label
seams that can withstand the elevated temperatures of a shrink
tunnel without sacrificing line speed. Also disclosed are labeled
containers and a process for applying a roll-on, shrink label to a
container using the hot-melt adhesives of the invention.
Inventors: |
Shelby; Marcus David; (Fall
Branch, TN) ; George; Scott Ellery; (Kingsport,
TN) ; Robe; Gary Robert; (Kingsport, TN) ;
Williams; Freddie Wayne; (Kingsport, TN) ; Donelson;
Michael Eugene; (Kingsport, TN) ; Cannon; Joshua
Seth; (Greeneville, TN) ; Tanner; Candace
Michele; (Kingsport, TN) |
Correspondence
Address: |
ERIC D. MIDDLEMAS;EASTMAN CHEMICAL COMPANY
P. O. BOX 511
KINGSPORT
TN
37662-5075
US
|
Assignee: |
Eastman Chemical Company
Kingsport
TN
|
Family ID: |
42131778 |
Appl. No.: |
12/577333 |
Filed: |
October 12, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61109545 |
Oct 30, 2008 |
|
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Current U.S.
Class: |
428/35.7 ;
156/85; 524/210; 524/270; 524/287; 524/513; 524/539; 524/605 |
Current CPC
Class: |
C09J 167/02 20130101;
Y10T 428/3179 20150401; Y10T 428/1331 20150115; Y10T 428/28
20150115; Y10T 428/4935 20150401; Y10T 428/2813 20150115; Y10T
428/2826 20150115; C08G 63/199 20130101; Y10T 428/1352 20150115;
Y10T 428/2852 20150115; B32B 2037/1215 20130101; Y10T 428/31786
20150401 |
Class at
Publication: |
428/35.7 ;
524/605; 524/270; 524/513; 524/539; 524/210; 524/287; 156/85 |
International
Class: |
C09J 133/04 20060101
C09J133/04; C09J 193/04 20060101 C09J193/04; B32B 1/00 20060101
B32B001/00; B32B 38/00 20060101 B32B038/00 |
Claims
1. A hot-melt adhesive composition, comprising: A. about 50 to 100
weight percent, based on the total weight of said adhesive
composition, of at least one polyester, comprising (i) diacid
residues, comprising about 30 to 60 mole percent, based on the
total moles of diacid residues, of the residues of adipic acid,
glutaric acid, or a combination thereof, about 30 to about 60 mole
percent of the residues of terephthalic acid, and about 0 to about
40 mole percent of at least one modifying dicarboxylic acid having
about 4 to about 40 carbon atoms; and (ii) diol residues,
comprising about 80 to about 100 mole percent, based on the total
moles of diol residues, of the residues of 1,4-butanediol,
1,6-hexanediol, or a combination thereof; and about 0 to about 20
mole percent of the residues of at least one modifying diol; and B.
0 to about 50 weight percent of a tackifier, plasticizer, wax,
nucleator, or combination thereof; wherein said polyester has an
inherent viscosity of about 0.1 to about 0.35 dL/g as measured at
25.degree. C. using 0.5 grams of polymer per 100 ml of a solvent
comprising 60 weight percent phenol and 40 weight %
tetrachloroethane, a melting temperature of about 70 to about
130.degree. C., and a heat of melting of about 0.1 cal/g to about 6
cal/g, and wherein said adhesive composition has a melt viscosity
of about 300 to about 3000 centipoise at 150.degree. C.
2. The adhesive composition according to claim 1, wherein said
modifying dicarboxylic acid comprises succinic acid, suberic acid,
pimelic acid, fumaric acid, maleic acid, itaconic acid, glycolic
acid sebacic acid, azelaic acid, dimer acid, isophthalic acid,
1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid,
or combinations thereof; and said modifying diol comprises
1,4-cyclohexanedimethanol, ethylene glycol, 1,2-propanediol,
1,3-propanediol, 1,5-pentanediol, neopentyl glycol, diethylene
glycol, triethylene glycol, 1,8-octanediol,
2,2,4-trimethyl-1,3-pentanediol, polyethylene glycol, polypropylene
glycol, 2,4-dimethyl-2-ethylhexane-1,3-diol;
2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol,
2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol,
1,5-pentanediol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, or
combinations thereof.
3. The adhesive composition according to claim 2, wherein said
diacid residues comprise about 30 about to about 60 mole percent of
the residues of adipic acid, about 30 to about 50 mole percent of
the residues of terephthalic acid, and 0 to about 30 mole percent
of the residues of said modifying dicarboxylic acid; and said diol
residues comprise about 90 to 100 mole percent of the residues of
1,4-butanediol, and 0 to about 10 mole percent of the residues of
said modifying diol.
4. The adhesive composition according to claim 3 wherein said
modifying dicarboxylic acid comprises isophthalic acid; and said
modifying diol comprises diethylene glycol,
1,4-cyclohexanedimethanol, or a combination thereof.
5. The adhesive composition according to claim 4 wherein said
diacid residues comprise about 40 to about 60 mole percent of the
residues of adipic acid, about 30 to about 45 mole percent of the
residues of terephthalic acid, and about 5 to about 30 mole percent
of the residues of said modifying dicarboxylic acid; and said
modifying diol comprises 1,4-cyclohexanedimethanol.
6. The adhesive composition according to claim 1 wherein said
tackifier comprises a tall oil rosin, gum rosin, wood rosin,
hydrogenated rosin, polymerized rosin, disproportionated rosin,
aromatic hydrocarbon resin, coumarone-indene resin, polyterpene,
terpene-phenolic resin, phenolic resin, maleic resin, ketone resin,
polyester resin, or combinations thereof; said plasticizer
comprises a benzoate ester, phthalate ester, citrate ester,
phosphate ester, terephthalate ester, isophthalate ester, or
combinations thereof; said wax comprises stearamide,
12-hydroxystearamide, N-(2-hydroxy ethyl)-12-hydroxystearamide,
glycerin monostearate, sorbitan monostearate, 12-hydroxy stearic
acid, or combinations thereof; and said nucleator comprises a
polyolefin or olefinic ionomer having a melting temperature of
about 70 to about 130.degree. C., or a mixture thereof.
7. The adhesive composition according to claim 6 wherein said
tackifier comprises at least one hydrogenated rosin having an acid
number of about 145 to about 160 mg KOH/gram of rosin; said
plasticizer comprises 1,4-cyclohexanedimethanol dibenzoate,
neopentyl glycol dibenzoate, dipropylene glycol dibenzoate,
propylene glycol dibenzoate, isodecyl benzoate, alkyl benzoate
esters having 7 to 40 carbon atoms, or combinations thereof; and
said nucleator comprises polyethylene, polypropylene, olefinic
ionomers, or combinations thereof.
8. The adhesive composition according to claim 7 which comprises
about 50 to about 70 weight percent of said polyester, about 20 to
about 40 weight percent of said hydrogenated rosin, and about 5 to
about 15 weight percent of a plasticizer comprising
1,4-cyclohexanedimethanol dibenzoate; a wax comprising stearamide,
12-hydroxystearamide, N-(2-hydroxy ethyl)-12-hydroxystearamide or a
combination thereof; or a combination of said plasticizer and
wax.
9. The adhesive composition according to claim 1 wherein said
polyester has a heat of melting of about 0.1 to about 4 cal/g.
10. The adhesive composition according to claim 7 which comprises
about 0.1 to about 5 weight percent of said nucleator.
11. A container, comprising a label adhered thereto with a hot-melt
adhesive composition, comprising A. about 50 to 100 weight percent,
based on the total weight of said adhesive composition, of at least
one polyester, comprising (i) diacid residues, comprising about 30
to 60 mole percent, based on the total moles of diacid residues, of
the residues of adipic acid, glutaric acid, or a combination
thereof, about 30 to about 60 mole percent of the residues of
terephthalic acid, and about 0 to about 40 mole percent of at least
one modifying dicarboxylic acid having about 4 to about 40 carbon
atoms; and (ii) diol residues, comprising about 80 to about 100
mole percent, based on the total moles of diol residues, of the
residues of 1,4-butanediol, 1,6-hexanediol, or a combination
thereof; and about 0 to about 20 mole percent of the residues of at
least one modifying diol; and; B. 0 to about 50 weight percent of a
tackifier, plasticizer, wax, nucleator, or combination thereof;
wherein said polyester has an inherent viscosity of about 0.1 to
about 0.35 dL/g as measured at 25.degree. C. using 0.5 grams of
polymer per 100 ml of a solvent comprising 60 weight percent phenol
and 40 weight % tetrachloroethane, a melting temperature of about
70 to about 130.degree. C., and a heat of melting of about 0.1
cal/g to about 6 cal/g, and wherein said adhesive composition has a
melt viscosity of about 300 to about 3000 centipoise at 150.degree.
C.
12. The container according to claim 11, wherein said modifying
dicarboxylic acid of said polyester comprises succinic acid,
suberic acid, pimelic acid, fumaric acid, maleic acid, itaconic
acid, glycolic acid sebacic acid, azelaic acid, dimer acid,
isophthalic acid, 1,3-cyclohexanedicarboxylic acid,
1,4-cyclohexanedicarboxylic acid, or combinations thereof; and said
modifying diol of said polyester comprises
1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol,
ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,5-pentanediol,
neopentyl glycol, diethylene glycol, triethylene glycol,
1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, polyethylene
glycol, polypropylene glycol, 2,4-dimethyl-2-ethylhexane-1,3-diol;
2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol,
2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol,
1,5-pentanediol, or combinations thereof.
13. The container according to claim 12, wherein said diacid
residues comprise about 30 about to about 60 mole percent of the
residues of adipic acid, about 30 to about 50 mole percent of the
residues of terephthalic acid, and 0 to about 30 mole percent of
the residues of said modifying dicarboxylic acid comprising
isophthalic acid; and said diol residues comprise about 90 to 100
mole percent of the residues of 1,4-butanediol, and 0 to about 10
mole percent of the residues of diethylene glycol,
1,4-cyclohexanedimethanol, or a combination thereof.
14. The container according to claim 13 wherein said diacid
residues comprise about 40 to about 60 mole percent of the residues
of adipic acid, about 30 to about 45 mole percent of the residues
of terephthalic acid, and about 5 to about 30 mole percent of the
residues of said modifying dicarboxylic acid; and said diol
residues comprise 0 to about 10 mole percent of the residues of
1,4-cyclohexanedimethanol.
15. The container according to claim 14 wherein said tackifier
comprises a tall oil rosin, gum rosin, wood rosin, hydrogenated
rosin, polymerized rosin, disproportionated rosin, aromatic
hydrocarbon resin, coumarone-indene resin, polyterpenes,
terpene-phenolic resin, phenolic resin, maleic resin, ketone resin,
polyester resin, or combinations thereof; said plasticizer
comprises a benzoate ester, phthalate ester, citrate ester,
phosphate ester, terephthalate ester, isophthalate ester, or
combinations thereof; said wax comprises stearamide,
12-hydroxystearamide, N-(2-hydroxy ethyl)-12-hydroxystearamide,
glycerin monostearate, sorbitan monostearate, 12-hydroxy stearic
acid, or combinations thereof; and said nucleator comprises a
polyolefin or olefinic ionomer having a melting temperature of
about 70 to about 130.degree. C., or a combination thereof.
17. The container according to claim 16 wherein said adhesive
composition comprises about 50 to about 70 weight percent of said
polyester, about 20 to about 40 weight percent of a tackifier
comprising a hydrogenated rosin, and about 5 to about 15 weight
percent of a plasticizer comprising 1,4-cyclohexanedimethanol
dibenzoate; a wax comprising stearamide, 12-hydroxystearamide,
N-(2-hydroxy ethyl)-12-hydroxystearamide or a combination thereof;
or a combination of said plasticizer and wax.
18. The container according to claim 11 wherein said polyester has
a heat of melting of about 0.1 to about 4 cal/g and a melting
temperature of about 90 to about 120.degree. C.
19. The container according to claim 11 wherein said label has at
least one layer and comprises a polyester, polyolefin,
polyvinylchloride, polylactic acid, paper, metal, or polystyrene
film.
20. The container according to claim 19 wherein said label is a
shrink label.
21. The container according to claim 20, wherein said label
comprises a polyester film comprising about 90 to about 100 mole
percent of the residues of terephthalic acid, based on the total
moles of diacid residues; and about 52 to about 88 mole percent of
the residues of ethylene glycol, based on the total moles of diol
residues, about 10 to about 28 mole percent of the residues of
1,4-cyclohexanedimethanol, and about 2 to about 20 mole percent of
the residues of diethylene glycol.
22. The container according to claim 21 wherein said label has
about 25 to about 85 percent machine direction shrinkage and 0 to
about 10 percent transverse direction shrinkage or growth.
23. The container according to claim 22 wherein said polyester
label further comprises a voiding agent, comprising at least one
polymer incompatible with said polyester film and dispersed
therein.
24. The container according to claim 11 which is a bottle, jar,
can, box, or battery casing.
25. A process for applying a roll-on, shrink label to a container,
comprising: I. applying a hot-melt adhesive to one or more
locations on a heat-shrinkable label, a container, or a combination
thereof, wherein said hot-melt adhesive comprises A. about 50 to
100 weight percent, based on the total weight of said adhesive
composition, of at least one polyester, comprising (i) diacid
residues, comprising about 30 to 60 mole percent, based on the
total moles of diacid residues, of the residues of adipic acid,
glutaric acid, or a combination thereof, about 30 to about 60 mole
percent of the residues of terephthalic acid, and about 0 to about
40 mole percent of at least one modifying dicarboxylic acid having
about 4 to about 40 carbon atoms; and (ii) diol residues,
comprising about 80 to about 100 mole percent, based on the total
moles of diol residues, of the residues of 1,4-butanediol,
1,6-hexanediol, or a combination thereof; and about 0 to about 20
mole percent of the residues of at least one modifying diol; and B.
0 to about 50 weight percent of a tackifier, plasticizer, wax,
nucleator, or combination thereof; wherein said polyester has an
inherent viscosity of about 0.1 to about 0.35 dL/g as measured at
25.degree. C. using 0.5 grams of polymer per 100 ml of a solvent
comprising 60 weight percent phenol and 40 weight %
tetrachloroethane, a melting temperature of about 70 to about
130.degree. C., and a heat of melting of about 0.1 cal/g to about 6
cal/g; and said adhesive composition has a melt viscosity of about
300 to about 3000 centipoise at 150.degree. C.; II. affixing said
label around said container to produce a labeled container; III.
allowing said applied hot-melt adhesive to at least partially
crystallize; and IV. shrinking said label by exposing said labeled
container to heat.
26. The process according to claim 25 wherein said diacid residues
comprise about 30 about to about 60 mole percent of the residues of
adipic acid, about 30 to about 50 mole percent of the residues of
terephthalic acid and 0 to about 30 mole percent of the residues of
isophthalic acid; and said diol residues comprise 0 to about 20
mole percent of the residues of 1,4-cyclohexanedimethanol,
diethylene glycol, or a combination thereof.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application Ser. No. 61/109,545, filed Oct. 30, 2008.
FIELD OF THE INVENTION
[0002] This invention pertains to hot melt adhesives. More
specifically, this invention pertains to hot-melt adhesives that
comprise a low molecular weight, aromatic-aliphatic polyester
comprising the residues of adipic acid, glutaric acid, or a
combination thereof, and terephthalic acid; 1,4-butanediol,
1,6-hexanediol, or a combination thereof; and optionally a
tackifier, plasticizer, wax, or a nucleator. These adhesives can be
used for multiple applications, but are particularly useful for
roll-applied shrink labels.
BACKGROUND OF THE INVENTION
[0003] Traditional, non-shrink labels frequently are prepared from
paper, foil, polypropylene film, and the like, and are applied to a
container by way of a "roll-fed" process in which the label is
simultaneously wrapped around and glued to the container. The
adhesive is typically a hot melt adhesive such as, for example, a
styrenic block copolymer or ethylene vinyl acetate, which is
applied both to the label seam to adhere the label to itself
("seaming") and to the container to hold the label in place.
[0004] Hot melt adhesives are thermoplastic materials which are
solid at room temperature. When heated to a liquid or molten form,
the hot melt adhesive can be applied to one or more surfaces that
are joined together as the hot melt adhesive cools back to a solid.
There are no special requirements for the adhesive for non-shrink
labels, other than providing enough strength to hold the label in
place during typical handling procedures. In addition, because
non-shrink labels are dimensionally stable (i.e., do not shrink),
the adhesive can be applied over a wide range of temperatures
without risk of prematurely shrinking or curling the label
seam.
[0005] The adhesives used for non-shrink labels generally are not
satisfactory for shrink labels, however. Because shrink labels
deform when heated above their "shrink onset" temperature (i.e.,
the temperature at which shrinkage occurs), the adhesive must be
applied at a temperature that will avoid premature curling and
shrinking of the label. Further, after a shrink label is seamed, it
must pass through a heat tunnel in order to shrink the label onto
the underlying container. In the shrink tunnel, the adhesive must
be able to withstand elevated temperatures and the force from the
shrink label, which will tend to pull the label seam apart. Hence,
the adhesive seam for a shrink label typically will have greater
strength than a seam in a non-shrink label, and should be able to
maintain this strength at the elevated temperatures of a shrink
tunnel.
[0006] The hot melt adhesives that are used now with roll-on
shrink-on labels are limited to applications involving low
shrinkage films (e.g., having 15% shrinkage or less), such as, for
example, labels prepared from a polypropylene substrate. Because
these films have low shrink force and shrinkage, separation of the
seam and curling of the label do not occur.
[0007] By contrast, labels prepared from other polymers such as,
for example, polyesters, polystyrene, poly(vinyl chloride), and
poly(lactic acid), can have much greater shrinkage and shrink
forces than materials that are now being used for roll-applied
shrink-on applications. For example, labels prepared from polyester
polymers can have 20 to 80% shrinkage. This high shrinkage enables
the shrink label to tightly fit against highly contoured containers
and results in a more aesthetically pleasing package. New hot melt
adhesives are needed for roll-applied shrink labels that provide
sufficient bond strength to withstand high shrink forces and
elevated temperatures and can be applied at a temperature that does
not cause premature shrinkage or curling of the film.
SUMMARY OF THE INVENTION
[0008] We have discovered hot-melt adhesive compositions comprising
at least 50 weight percent of a polyester that can be applied at
temperatures below the shrink onset temperature of high shrinkage
films and can withstand high shrink forces at the elevated
temperatures commonly used in shrink tunnels. Thus, in one
embodiment, our invention provides a hot-melt adhesive composition,
comprising:
A. A hot-melt adhesive composition, comprising: [0009] A. about 50
to 100 weight percent, based on the total weight of the adhesive
composition, of at least one polyester, comprising (i) diacid
residues, comprising about 30 to 60 mole percent, based on the
total moles of diacid residues, of the residues of adipic acid,
glutaric acid, or a combination thereof, about 30 to about 60 mole
percent of the residues of terephthalic acid, and about 0 to about
40 mole percent of at least one modifying dicarboxylic acid having
about 4 to about 40 carbon atoms; and (ii) diol residues,
comprising about 80 to about 100 mole percent, based on the total
moles of diol residues, of the residues of 1,4-butanediol,
1,6-hexanediol, or a combination thereof; and about 0 to about 20
mole percent of the residues of at least one modifying diol; and
[0010] B. 0 to about 50 weight percent of a tackifier, plasticizer,
wax, nucleator, or combination thereof; [0011] wherein the
polyester has an inherent viscosity of about 0.1 to about 0.4 dL/g
as measured at 25.degree. C. using 0.5 grams of polymer per 100 ml
of a solvent comprising 60 weight percent phenol and 40 weight %
tetrachloroethane, a melting temperature of about 70 to about
130.degree. C., and a heat of melting of about 0.1 cal/g to about 6
cal/g; and [0012] wherein the adhesive composition has a melt
viscosity of about 300 to about 3000 centipoise at 150.degree. C.
The hot melt adhesives of the present invention can be used in a
wide variety of applications, particularly those requiring a rapid
crystallization time within a controlled temperature window. Our
hot-melt adhesive can be applied as a liquid and provides excellent
bond strength at temperatures above the initial application
temperature. This characteristic is of particular benefit when
bonding substrates that are thermally sensitive and/or thermally
activated such as, for example, roll-applied shrink labels having a
high degree of shrinkage.
[0013] Our adhesive composition is useful for adhering roll-applied
shrink labels to containers. Another embodiment of the invention,
therefore, is a container comprising a label adhered thereto with a
hot-melt adhesive composition, comprising [0014] A. about 50 to 100
weight percent, based on the total weight of the adhesive
composition, of at least one polyester, comprising (i) diacid
residues, comprising about 30 to 60 mole percent, based on the
total moles of diacid residues, of the residues of adipic acid,
glutaric acid, or a combination thereof, about 30 to about 60 mole
percent of the residues of terephthalic acid, and about 0 to about
40 mole percent of at least one modifying dicarboxylic acid having
about 4 to about 40 carbon atoms; and (ii) diol residues,
comprising about 80 to about 100 mole percent, based on the total
moles of diol residues, of the residues of 1,4-butanediol,
1,6-hexanediol, or a combination thereof; and about 0 to about 20
mole percent of the residues of at least one modifying diol; and
[0015] B. 0 to about 50 weight percent of a tackifier, plasticizer,
wax, nucleator, or combination thereof;
[0016] wherein the polyester has an inherent viscosity of about 0.1
to about 0.35 dL/g as measured at 25.degree. C. using 0.5 grams of
polymer per 100 ml of a solvent comprising 60 weight percent phenol
and 40 weight % tetrachloroethane, a melting temperature of about
70 to about 130.degree. C., and a heat of melting of about 0.1
cal/g to about 6 cal/g; and
[0017] wherein the adhesive composition has a melt viscosity of
about 300 to about 3000 centipoise at 150.degree. C.
[0018] Our invention also provides a process for applying a
roll-on, shrink label to a container, comprising: [0019] I.
applying a hot-melt adhesive to one or more locations on a
heat-shrinkable label, a container, or a combination thereof,
wherein the hot-melt adhesive comprises [0020] A. about 50 to 100
weight percent, based on the total weight of the adhesive
composition, of at least one polyester, comprising (i) diacid
residues, comprising about 30 to 60 mole percent, based on the
total moles of diacid residues, of the residues of adipic acid,
glutaric acid, or a combination thereof, about 30 to about 60 mole
percent of the residues of terephthalic acid, and about 0 to about
40 mole percent of at least one modifying dicarboxylic acid having
about 4 to about 40 carbon atoms; and (ii) diol residues,
comprising about 80 to about 100 mole percent, based on the total
moles of diol residues, of the residues of 1,4-butanediol,
1,6-hexanediol, or a combination thereof; and about 0 to about 20
mole percent of the residues of at least one modifying diol; and
[0021] B. 0 to about 50 weight percent of a tackifier, plasticizer,
wax, nucleator, or combination thereof; [0022] wherein the
polyester has an inherent viscosity of about 0.1 to about 0.35 dL/g
as measured at 25.degree. C. using 0.5 grams of polymer per 100 ml
of a solvent comprising 60 weight percent phenol and 40 weight %
tetrachloroethane, a melting temperature of about 70 to about
120.degree. C., and a heat of melting of about 0.1 cal/g to about 6
cal/g; and [0023] wherein the adhesive composition has a melt
viscosity of about 300 to about 3000 centipoise at 150.degree. C.;
[0024] II. affixing the label around the container to produce a
labeled container; [0025] III. allowing the applied hot-melt
adhesive to at least partially crystallize; and [0026] IV.
shrinking the label by exposing the labeled container to heat.
DETAILED DESCRIPTION
[0027] The hot-melt adhesive composition of the invention comprises
at least 50 weight percent of a polyester and is particularly
useful for roll-applied shrink labels in which the films exhibit
high shrinkage (e.g., about 25-75%) and shrink force. In a general
embodiment, our hot-melt adhesive composition comprises: [0028] A.
about 50 to 100 weight percent, based on the total weight of the
adhesive composition, of at least one polyester, comprising (i)
diacid residues, comprising about 30 to 60 mole percent, based on
the total moles of diacid residues, of the residues of adipic acid,
glutaric acid, or a combination thereof, about 30 to about 60 mole
percent of the residues of terephthalic acid, and about 0 to about
40 mole percent of at least one modifying dicarboxylic acid having
about 4 to about 40 carbon atoms; and (ii) diol residues,
comprising about 80 to about 100 mole percent, based on the total
moles of diol residues, of the residues of 1,4-butanediol,
1,6-hexanediol, or a combination thereof; and about 0 to about 20
mole percent of the residues of at least one modifying diol; and
[0029] B. 0 to about 50 weight percent of a tackifier, plasticizer,
wax, nucleator, or combination thereof;
[0030] wherein the polyester has an inherent viscosity of about 0.1
to about 0.4 dL/g as measured at 25.degree. C. using 0.5 grams of
polymer per 100 ml of a solvent comprising 60 weight percent phenol
and 40 weight % tetrachloroethane, a melting temperature of about
70 to about 130.degree. C., and a heat of melting of about 0.1
cal/g to about 6 cal/g; and
[0031] wherein the adhesive composition has a melt viscosity of
about 300 to about 3000 centipoise at 150.degree. C.
The hot melt adhesive of the present invention can be used in a
wide variety of applications, particularly those requiring rapid
crystallization and high bond strength at temperatures above the
initial application temperature. The hot-melt adhesives of the
invention are useful for polyester, roll-applied shrink labels.
[0032] Unless otherwise indicated, all numbers expressing
quantities of ingredients, properties such as molecular weight,
reaction conditions, and so forth used in the specification and
claims are to be understood as being modified in all instances by
the term "about." Accordingly, unless indicated to the contrary,
the numerical parameters set forth in the following specification
and attached claims are approximations that may vary depending upon
the desired properties sought to be obtained by the present
invention. At the very least, each numerical parameter should at
least be construed in light of the number of reported significant
digits and by applying ordinary rounding techniques. Further, the
ranges stated in this disclosure and the claims are intended to
include the entire range specifically and not just the endpoint(s).
For example, a range stated to be 0 to 10 is intended to disclose
all whole numbers between 0 and 10 such as, for example 1, 2, 3, 4,
etc., all fractional numbers between 0 and 10, for example 1.5,
2.3, 4.57, 6.1113, etc., and the endpoints 0 and 10. Also, a range
associated with chemical substituent groups such as, for example,
"C.sub.1 to C.sub.5 hydrocarbons", is intended to specifically
include and disclose C.sub.1 and C.sub.5 hydrocarbons as well as
C.sub.2, C.sub.3, and C.sub.4 hydrocarbons.
[0033] Notwithstanding that the numerical ranges and parameters
setting forth the broad scope of the invention are approximations,
the numerical values set forth in the specific examples are
reported as precisely as possible. Any numerical value, however,
inherently contains certain errors necessarily resulting from the
standard deviation found in their respective testing
measurements.
[0034] It is also to be understood that the mention of one or more
method steps does not preclude the presence of additional method
steps before or after the combined recited steps or intervening
method steps between those steps expressly identified. Moreover,
the lettering of process steps is a convenient means for
identifying discrete activities or steps, and unless otherwise
specified, recited process steps may be arranged in any
sequence.
[0035] The hot-melt adhesive of the present invention comprises a
thermoplastic polyester. The term "polyester", as used herein, is
intended to include "copolyesters" and is understood to mean a
synthetic polymer prepared by the polyesterification and
polycondensation of one or more difunctional carboxylic acids with
one or more difunctional hydroxyl compounds. Typically the
difunctional carboxylic acid is a dicarboxylic acid and the
difunctional hydroxyl compound is a dihydric alcohol such as, for
example, glycols and diols. Alternatively, the difunctional
carboxylic acid may be a hydroxy carboxylic acid such as, for
example, p-hydroxybenzoic acid, and the difunctional hydroxyl
compound may be an aromatic nucleus bearing 2 hydroxyl substituents
such as, for example, hydroquinone. The term "residue", as used
herein, means any organic structure incorporated into a polymer
through a polycondensation reaction involving the corresponding
monomer. The term "repeating unit", as used herein, means an
organic structure having a dicarboxylic acid residue and a diol
residue bonded through a carbonyloxy group. Thus, the dicarboxylic
acid residues may be derived from a dicarboxylic acid monomer or
its associated acid halides, esters, salts, anhydrides, or mixtures
thereof. As used herein, therefore, the term dicarboxylic acid is
intended to include dicarboxylic acids and any derivative of a
dicarboxylic acid, including its associated acid halides, esters,
half-esters, salts, half-salts, anhydrides, mixed anhydrides, or
mixtures thereof, useful in a polycondensation process with a diol
to make a polyester.
[0036] The expression "roll-on shrink-on" (abbreviated herein as
"ROSO"), as used herein, is understood to be synonymous with the
expression "roll-applied shrink-on" (abbreviated herein as "RAS"),
and refers to labels that are applied to a container by affixing
the label to the container and rolling or spinning the container to
wrap the label around the container. Typically, the labels are fed
to the labeling process from a roll, but also can be provided as
individual labels in what is known in the art as a "cut and stack"
process.
[0037] The term "substrate", as used herein, means a surface to
which the hot-melt adhesive is applied and adheres. Non-limiting
examples of substrates include films, bottles, boxes, jars, and the
like that can be prepared from materials such as, for example,
plastics, wood, metal, paper, glass, or combinations thereof.
[0038] The polyesters that are used in the hot-melt adhesives of
present invention comprise dicarboxylic acid residues and diol
residues. The polyesters of the present invention contain
substantially equal molar proportions of diacid residues (100 mole
percent) and diol residues (100 mole percent) which react in
substantially equal proportions such that the total moles of
repeating units is equal to 100 mole percent. The mole percentages
provided in the present disclosure, therefore, may be based on the
total moles of diacid residues, the total moles of diol residues,
or the total moles of repeating units. For example, a polyester
containing 30 mole percent adipic acid, based on the total diacid
residues, means the polyester contains 30 mole percent adipic acid
residues out of a total of 100 mole percent diacid residues. Thus,
there are 30 moles of adipic acid residues among every 100 moles of
diacid residues. In another example, a polyester containing 30 mole
percent 1,4-butanediol, based on the total diol residues, means the
polyester contains 30 mole percent 1,4-butanediol residues out of a
total of 100 mole percent diol residues. Thus, there are 30 moles
of 1,4-butanediol residues among every 100 moles of diol
residues.
[0039] The hot-melt adhesive of our invention comprises about 50 to
100 weight percent, based on the total weight of the adhesive
composition of a low-molecular weight, thermoplastic polyester as
its base material. The polyester comprises diacid residues
comprising about 30 to about 60 mole percent, based on the total
moles of diacid residues, of the residues of adipic acid, glutaric
acid, or a combination thereof, about 30 to about 60 mole percent
of the residues of terephthalic acid, and about 0 to about 40 mole
percent of at least one modifying dicarboxylic acid having about 4
to about 40 carbon atoms. For example, the polyester can have from
about 30 to about 60 mole percent of the residues of adipic acid or
glutaric acid, about 30 to about 50 mole percent of the residues of
terephthalic acid, and 0 to about 30 mole percent of the residues
of a modifying dicarboxylic acid. In another example, the polyester
can have about 35 to about 60 mole percent of the residues of
adipic or glutaric acid, about 35 to about 45 mole percent of the
residues of terephthalic acid and about 0 to about 30 mole percent
of a modifying dicarboxylic acid.
[0040] The polyester can comprise 0 to about 30 mole percent of the
residues of at least one modifying dicarboxylic acid having about 4
to about 40 carbon atoms. Some representative examples of modifying
dicarboxylic acids include, but are not limited to, succinic acid,
suberic acid, pimelic acid, fumaric acid, maleic acid, itaconic
acid, glycolic acid, sebacic acid, azelaic acid, dimer acid,
isophthalic acid, 1,3-cyclohexanedicarboxylic acid,
1,4-cyclohexanedicarboxylic acid, and combinations thereof. For
example, the modifying dicarboxylic acid can comprise isophthalic
acid. The polyester also may comprise the residues of dicarboxylic
acids containing specialized functionalities such as, for example,
5-sodiosulfoisophthalic, t-butyl isophthalic, 5-hydroxy
isophthalic, and 4,4'-sulfonyl dibenzoic. Where cis and trans
isomers are possible, the pure cis or trans or a mixture of cis and
trans isomers may be used.
[0041] The diol component of the base polyester comprises about 80
to about 100 mole percent, based on the total moles of diol
residues, of the residues of 1,4-butanediol, 1,6-hexanediol, or a
combination thereof; and about 0 to about 20 mole percent of the
residues of at least one modifying diol. For example, in one
embodiment of the invention, the polyester can comprise diol
residues comprising about 90 to 100 mole percent of the residues of
1,4-butanediol, and about 10 to about 0 mole percent of the
residues of a modifying diol. In another example, the polyester can
comprise about 100 percent of the residues of 1,6-hexanediol.
Examples of modifying diols include 1,4-cyclohexanedimethanol,
ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,5-pentanediol,
neopentyl glycol, diethylene glycol, triethylene glycol,
1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, polyethylene
glycol, polypropylene glycol, 2,4-dimethyl-2-ethylhexane-1,3-diol;
2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol,
2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol,
1,5-pentanediol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, or
combinations thereof.
[0042] As noted above, polyglycols such as, for example, diethylene
glycol, tetraethylene glycol, and polyalkylene glycols, may be used
in combination with 1,4-butanediol. Many of these glycols are
available commercially such as, for example, the polyalkylene
glycols produced by Dow Chemical Company under the CARBOWAX.TM.
trade name. The molecular weight of the polyalkylene glycols,
typically, will be from about 200 to about 10,000 g/mole. For
example, the polyester also may comprise the residues of higher
order alkyl analogs such as, for example, dipropylene glycol,
dibutylene glycol, and dihexylene glycol. Similarly, higher order
polyalkylene diols are useful, particularly polypropylene glycol
and polytetramethylene glycol with molecular weights ranging from
200 to 10,000 g/mole.
[0043] In one example, the polyester of the hot-melt adhesive
composition can comprise diacid residues comprising about 30 about
to about 60 mole percent of the residues of adipic acid, about 30
to about 50 mole percent of the residues of terephthalic acid, and
0 to about 30 mole percent of the residues of a modifying
dicarboxylic acid; and diol residues comprising about 90 to 100
mole percent of the residues of 1,4-butanediol, and 0 to about 10
mole percent of the residues of the modifying diol. In the above
embodiment, the above modifying dicarboxylic acid can comprise
isophthalic acid, and the modifying diol can comprise diethylene
glycol, 1,4-cyclohexanedimethanol, or a combination thereof.
[0044] In another example, the diacid residues comprise about 40 to
about 60 mole percent of the residues of adipic acid, about 30 to
about 45 mole percent of the residues of terephthalic acid, and
about 5 to about 30 mole percent of the residues of a modifying
dicarboxylic acid; and the diol residues comprise about 90 to 100
mole percent of the residues of 1,4-butanediol and about 10 to 0
mole percent of the residues of 1,4-cyclohexanedimethanol. The
modifying dicarboxylic acid can be isophthalic acid in the above
example.
[0045] The polyester of our novel hot-melt adhesive can have an
inherent viscosity of about 0.1 to about 0.35 dL/g as measured at
25.degree. C. using 0.5 grams of polymer per 100 ml of a solvent
comprising 60 weight percent phenol and 40 weight %
tetrachloroethane. Some additional examples of inherent viscosities
for the polyester are about 0.1 to about 0.33; about 0.1 to about
0.30; about 0.1 to about 0.27; about 0.1 to about 0.25; and about
0.1 to about 0.20. In order to achieve this relatively low
viscosity, the molecular weight of the polyester, typically, will
be in the range of about 1000 to about 15,000 g/mole. Some
additional examples of molecular weight ranges of the polyester are
about 1000 to about 13,000 g/mole, about 1000 to about 10,000
g/mole; and about 1000 to about 8000 g/mole.
[0046] The polyester can also incorporate from 0 to about 5 mole
percent of one or more monofunctional chain terminators to help
control the rate of polymerization. These chain terminators are
well known in the art. Some non-limiting examples of chain
terminators are one or more monofunctional linear aliphatic,
cycloaliphatic, or aromatic carboxylic acids or monofunctional
alcohols having 1 to about 36 carbon atoms. These chain terminators
can contain any functional group. The functional groups can be, for
example, an ionic end group such as, for example, sodiosulfobenzoic
acid, a reactive end group, or a combination thereof. These various
functional groups may be used to tailor the end groups of the
polyester to be more acidic or basic in nature. These modifications
can be useful, for example, to improve surface interaction between
adhesive and substrate, or to improve compatibility between the
adhesive and certain formulating ingredients.
[0047] The polyester typically will have a melting temperature of
about 70 to about 130.degree. C. Most polymers will exhibit one or
more smaller melting peaks by differential scanning calorimetry
("DSC") at temperatures below the primary melting temperature that
have characteristics (e.g., melting enthalpy and peak temperature)
that can be dependent on the thermal history of the polymer. The
term "melting temperature" (abbreviated herein as "Tm"), as used
herein, is defined as the peak temperature of the melting endotherm
of the 2nd heat cycle. For example, if multiple melting peaks are
present, then the highest peak melting temperature is considered
the melting temperature of the polyester in accordance with the
invention. Other examples of melting temperature ranges are about
80 to about 130.degree. C., about 80 to about 120.degree. C., about
90 to about 120.degree. C., and about 100 to about 120.degree. C.
It is also desirable for roll-applied shrink-on applications that
the molten polyester recrystallize below the shrink onset
temperature of the label. Thus, in one embodiment of the invention,
the polyester of the hot-melt adhesive has a recrystallization
temperature of about 0 to about 80.degree. C. Other examples of
recrystallization temperatures are about 0 to about 75.degree. C.,
about 0 to about 70.degree. C., about 0 to about 65.degree. C.,
about 0 to about 60.degree. C., about 0 to about 55.degree. C. and
about 0 to about 50.degree. C. The recrystallization temperature
can be determined by DSC as either the recrystallization
temperature upon heating "Tch" (at 20.degree. C./min) or upon
cooling "Tcc" (20.degree. C./min) as described herein.
[0048] The polyester has a heat of melting (abbreviated herein as
".DELTA.Hm") of about 0.1 cal/g to about 6 cal/g as measured by
differential scanning calorimetry. The heat of melting is
proportional to how much crystallinity is present in the polyester.
Typically, .DELTA.Hm is normalized by the weight of the sample
being tested and reported as either J/g or cal/g. Other examples of
heat of melting ranges are about 0.1 to about 4 cal/g, about 0.3 to
about 4 cal/g, and about 0.5 and 3 cal/g.
[0049] The heat of fusion (abbreviated herein as ".DELTA.Hf"), is
an intrinsic material parameter (i.e. it does not depend on heat
history) and represents the value of .DELTA.Hm that would be
obtained for a 100% crystalline solid. The value of .DELTA.Hf is a
theoretical number, and typically can be determined by correlating
and extrapolating DSC measurements with other measurements (e.g.
x-ray) or by theoretical calculation. The term "heat of fusion", as
used herein, is synonymous with the terms "enthalpy of fusion,"
"latent heat of fusion," "enthalpy change of fusion", and "specific
melting heat," and is understood to mean the amount of thermal
energy which must be absorbed or evolved for 1 gram of the
polyester to change states from a solid to a liquid or vice versa.
If the heat of fusion is known for a given polymer, then the %
crystallinity can be estimated by the following equation:
% crystallinity=.DELTA.Hm/.DELTA.Hf*100%
Typically, .DELTA.Hf is difficult to determine and is rarely
available. Because .DELTA.Hm, is directly proportional to
crystallinity of a polymer, .DELTA.Hm is reported herein as an
indirect measure of crystallinity.
[0050] The polyesters of the instant invention are readily prepared
from the appropriate dicarboxylic acids, esters, anhydrides, or
salts, and the appropriate diol or diol mixtures using typical
polycondensation reaction conditions by procedures known to persons
skilled in the art. They may be made by continuous,
semi-continuous, and batch modes of operation and may utilize a
variety of reactor types. Examples of suitable reactor types
include, but are not limited to, stirred tank, continuous stirred
tank, slurry, tubular, wiped-film, falling film, or extrusion
reactors. The reaction of the diol and dicarboxylic acid may be
carried out using conventional polyester polymerization conditions
or by melt phase processes. For example, when preparing the
polyester by means of an ester interchange reaction, i.e., from the
ester form of the dicarboxylic acid components, the reaction
process may comprise two steps. In the first step, the diol
component and the dicarboxylic acid component, such as, for
example, dimethyl terephthalate, are reacted at elevated
temperatures, typically, about 150.degree. C. to about 250.degree.
C. for about 0.5 to about 8 hours at pressures ranging from about
0.0 kPa gauge to about 414 kPa gauge (60 pounds per square inch,
"psig"). For example, the temperature for the ester interchange
reaction can range from about 180.degree. C. to about 230.degree.
C. for about 1 to about 4 hours while the pressure ranges from
about 103 kPa gauge (15 psig) to about 276 kPa gauge (40 psig).
Thereafter, the reaction product is heated under higher
temperatures and under reduced pressure to form the polyester with
the elimination of diol, which is readily volatilized under these
conditions and removed from the system. This second step, or
polycondensation step, is continued under higher vacuum and a
temperature which generally ranges from about 230.degree. C. to
about 350.degree. C. for about 0.1 to about 6 hours, until a
polymer having the desired degree of polymerization, as determined
by inherent viscosity, is obtained. The polycondensation step may
be conducted advantageously under reduced pressure which ranges
from about 53 kPa (400 torr) to about 0.013 kPa (0.1 torr).
Stirring or appropriate conditions are used in both stages to
ensure adequate heat transfer and surface renewal of the reaction
mixture. The reaction rates of both stages are increased by
appropriate catalysts such as, for example, alkoxy titanium
compounds, alkali metal hydroxides and alcoholates, salts of
organic carboxylic acids, alkyl tin compounds, metal oxides, and
the like. A three-stage manufacturing procedure, similar to that
described in U.S. Pat. No. 5,290,631, may also be used,
particularly when a mixed monomer feed of acids and esters is
employed.
[0051] To ensure that the reaction of the diol component and
dicarboxylic acid component by an ester interchange reaction is
driven to completion, it is sometimes desirable to employ about
1.05 to about 2.5 moles of diol component to one mole dicarboxylic
acid component. Persons of skill in the art will understand,
however, that the ratio of diol component to dicarboxylic acid
component is generally determined by the design of the reactor in
which the reaction process occurs.
[0052] In the preparation of polyester by direct esterification,
i.e., from the acid form of the dicarboxylic acid component,
polyesters are produced by reacting the dicarboxylic acid or a
mixture of dicarboxylic acids with the diol component or a mixture
of diol components. The reaction is conducted at a pressure of
about 7 kPa gauge (1 psig) to about 1379 kPa gauge (200 psig),
preferably less than 689 kPa (100 psig) to produce a low molecular
weight polyester product having an average degree of polymerization
of from about 1.4 to about 10. The temperatures employed during the
direct esterification reaction typically range from about
180.degree. C. to about 280.degree. C. This low molecular weight
polymer may then be polymerized by a polycondensation reaction.
[0053] Although the polyester may be used neat as the only
component of the hot-melt adhesive, the hot-melt adhesive
composition can also include blends of multiple polymers,
tackifiers, extenders, modifiers, adhesion promoters, nucleators,
rosins, and the like, to control rheology, crystallinity and
processability as needed. Other possible additives include
antioxidants, adhesion promoters or coupling agents (silane and
non-silane based), solvent, water, ultraviolet-light-curable
reactive oligomers, crosslinking agents, photoinitiators (reactive
resin prepolymer and/or photosensitizing agent), fillers
(reinforcing, neutralizing conductive, flame retardant, water
soluble, expandable), compatibilizers, detackifiers, flame proof
agents, polyethylene glycols ("PEGS"), indicators, metal particles,
toughening agents, waxes, reactive diluents, coloring agents and/or
pigments, thixotropic agents, chopped fiber, inorganics (silica,
carbonates, oxides, fluorides, talc, clay and sulfates), organics
(cellulose, jute), biocides, dessicants, blowing agents,
humectants, and impact modifiers. The adhesive can also be a blend
of one or more polymers, which might be useful, for example, when
two or more substrates of differing materials are involved.
[0054] For example, the adhesive composition can comprise up to 50
weight percent of a tackifier, plasticizer, wax, nucleator, or
combinations thereof. Some non-limiting examples of tackifiers
include tall oil, gum or wood rosin either unmodified, partially
hydrogenated, fully hydrogenated or disproportionated, polymerized
rosins, rosin derivatives such as rosin esters, phenolic modified
rosin esters, acid modified rosin esters, distilled rosin,
dimerized rosin, maleated rosin, and polymerized rosin; hydrocarbon
resins including aliphatic and aromatic resins, coumarone-indene
resins, polyterpenes, terpene-phenolic resins, phenolic resins,
maleic resins, ketone resins, reactive resins, hybrid resins, and
polyester resins. In one embodiment, for example, the tackifier can
comprise a tall oil rosin, gum rosin, wood rosin, hydrogenated
rosin, polymerized rosin, disproportionated rosin, aromatic
hydrocarbon resin, coumarone-indene resin, polyterpene,
terpene-phenolic resin, phenolic resin, maleic resin, ketone resin,
polyester resin, or combinations thereof. The hydrocarbon resins
can be hydrogenated or partially hydrogenated. Some further
examples of tackifiers can be found in U.S. Pat. Nos. 5,418,052;
5,442,001; and 5,532,306. Other examples of tackifiers include, but
are not limited to, styrene and alpha methyl styrene resins,
glycerol and pentaerithritol esters, and the like. Some examples of
tackifiers that are available commercially include WINGTACK 95.TM.
(available from Goodyear), EASTOTAC H100.TM. and KRYSTALEX.TM. 3100
(both available from Eastman Chemical Co.), and ECR 149B.TM. or ECR
179A.TM. (available from Exxon Chemical Co.) Other tackifiers
include rosin and its derivatives available from Reichold
Chemicals. In one example, the adhesive comprises a tackifier
comprising at least one hydrogenated rosin having an acid number of
about 145 to about 175 mg KOH/gram of rosin.
[0055] The adhesive composition also can comprise one or more
plasticizers to reduce the glass transition temperature and/or the
viscosity of the polyester component. Examples of plasticizers
include benzoate esters, phthalate esters, citrate esters,
phosphate esters, terephthalate esters, isophthalate esters, or
combinations thereof. Some examples of phthalate plasticizers
include dioctyl phthalate and butyl benzyl phthalate; liquid
polyesters (non-crystalline) such as DYNACOL 720.TM. (available
from Huls); benzoate plasticizers such as 1,4-cyclohexane
dimethanol dibenzoate (e.g., BENZOFLEX 352.TM. available
commercially from Velsicol), diethylene glycol/dipropylene glycol
dibenzoate (e.g., BENZOFLEX 50.TM. available commercially from
Velsicol) and diethylene glycol dibenzoate where the mole fraction
of hydroxyl groups which have been esterified ranges from 0.5 to
0.95 (e.g., BENZOFLEX 2-45.TM. High Hydroxyl also from Velsicol);
phosphate plasticizers such as t-butylphenyl diphenyl phosphate
(e.g., SANTICIZER.TM., available commercially from Ferro
Corporation); poly(ethylene glycol) with molecular weights below
about 1000 and derivatives of poly(ethylene glycol) (e.g.,
PYCA.TM.L 94, the phenyl ether of PEG, available commercially from
ICI); ethoxylated bis phenol A (e.g., MACOL 206 EM from PPG
Industries); dinonyl phenol ethoxylates (e.g., SURFONIC.TM. DNP
100, available commercially from Huntsman Chemical Corp.); as well
as vegetable and animal oils such as glycerol esters of fatty acids
and polymerization products thereof. For example, the adhesive
composition can comprise benzoate esters such as
1,4-cyclohexanedimethanol dibenzoate, neopentyl glycol dibenzoate,
dipropylene glycol dibenzoate, propylene glycol dibenzoate,
isodecyl benzoate, alkyl benzoate ester, or combinations
thereof.
[0056] The adhesive composition also can comprise one or more
compatible waxes to improve the bond strength, prevent or reduce
cold flow, and to decrease set time. Some representative examples
of compatible waxes are described in U.S. Pat. No. 5,750,605. These
compounds generally have molecular weights below 500 g/mole with at
least one polar group to facilitate compatibility with the base
polyester and a crystalline melting point. Higher concentrations of
polar groups are necessary for higher molecular weight waxes. These
polar groups include hydroxyls, amides (primary, secondary, and
tertiary), sulfones, phosphate esters, sulfonamides, carbonates,
ureas, amines, urethanes, and carboxylic acids; and carboxylate,
urea, and sulfonate salts. For example, some waxes that can be used
in the adhesive composition include 12-hydroxystearamide,
N-(2-hydroxy ethyl)-12-hydroxystearamide, known by the trademark
PARICIN.TM. 220 (available from CasChem), stearamide, known as
KENAMIDE.TM. S (available from Witco), glycerin monostearate,
sorbitan monostearate, and 12-hydroxy stearic acid. Also useful in
combination with the above are the less polar waxes such as
N,N'-ethylene-bis-stearamide (KEMAMIDE.TM. W-40 from Witco),
hydrogenated castor oil (castor wax), oxidized synthetic waxes, and
functionalized synthetic waxes such as oxidized polyethylene waxes
(PETROLITE.TM. E-1040).
[0057] Nucleators may be used with the adhesive composition to
modify and control crystallinity formation. The term "nucleator",
as used herein, is intended to be synonymous with the term
"nucleating agent" and refers to a chemical substance which, when
incorporated into polymers, form nuclei for the growth of crystals
in the polymer melt. Any incompatible material can serve as a
nucleator provided that it rapidly separates into particles as the
molten adhesive cools. A variety of organic and inorganic
nucleators well-known in the art can be used. For example, in one
embodiment of the invention, the adhesive composition comprises one
or more nucleators comprising a low molecular weight polyolefin
and/or olefinic ionomer with melting temperature ranging from about
70.degree. C. to 130.degree. C.
[0058] In one example, our inventive adhesive composition can
comprise a tackifier comprising at least one hydrogenated rosin
having an acid number of about 145 to about 175 mg KOH/gram of
rosin; a plasticizer comprising 1,4-cyclohexanedimethanol
dibenzoate, neopentyl glycol dibenzoate, dipropylene glycol
dibenzoate, propylene glycol dibenzoate, isodecyl benzoate, alkyl
benzoate esters having 7 to 40 carbon atoms, or combinations
thereof; and a nucleator comprising polyethylene, polypropylene,
olefinic ionomers, or combinations thereof. In another embodiment,
the adhesive composition can comprise about 50 to about 70 weight
percent of a polyester as set forth above, about 20 to about 40
weight percent of a hydrogenated rosin, and about 5 to about 15
weight percent of a plasticizer comprising
1,4-cyclohexanedimethanol dibenzoate; a wax comprising stearamide,
12-hydroxystearamide, N-(2-hydroxy ethyl)-12-hydroxystearamide, or
a combination thereof; or a combination of the plasticizer and
wax.
[0059] The adhesive of the present invention can be blended with
other polymers to extend or enhance performance. These polymers
include, but are not limited to polyolefins, amorphous polyolefins,
copolyester, sulfopolyesters, polyurethanes, polyamides,
ethylene-vinyl acetate (EVA), vinyl acetate-ethylene (VAE), natural
rubber, polybutenes, polyisobutylene, styrene-butadiene rubber,
styrenic di-, tri- and multi-block copolymers
(styrene-isoprene-styrene, styrene-butadiene-styrene,
styrene-ethylene/propene-styrene, styrene-ethylene/butene-styrene,
styrene-isoprene/butadiene-styrene), nitrile rubber,
ethylene-propylene-diene modified rubber, silicones,
vinylpyrrolidones, ethylene acrylics, polyvinyl alcohols, acrylics,
and blends thereof. Also included are functionalized polymers such
as, for example, epoxidized or carboxyl terminated polymers.
[0060] The adhesive composition typically has a melt viscosity from
about 300 to about 3000 centipoise at 150.degree. C. Melt viscosity
can be determined using methods well known in art such as, for
example, using a Brookfield DVII Viscometer equipped with a
thermosel and number 27 spindle in accordance with ASTM Method
D3236, "Apparent Viscosity of Hot Melt Adhesives and Coating
Materials". Additional examples of the melt viscosity at
150.degree. C. are about 300 to about 2500 centipoise, about 300 to
about 2000 centipoise, about 500 to about 2500 centipoise, about
300 to about 700 centipoise, and 1000 centipoise or less. When the
hot melt adhesive composition is used for shrink labels, it is
generally desirable for the melt viscosity of the adhesive to be at
or below about 3000 centipoise, or in another embodiment, at or
below about 2000 centipoise, at the shrink onset temperature
("T.sub.so") of the label+about 80.degree. C. For example, the
shrink onset temperature for many films that are used for RAS
applications is approximately 70.degree. C.; thus, the temperature
for the latter melt viscosities of the hot melt adhesive
composition is about T.sub.so+80.degree. C.=150.degree. C. Persons
skilled in the art will understand that the above temperatures and
viscosities can be adjusted in accordance with the shrink onset
temperatures of the film substrates. It should be noted that the
above viscosities are for the formulated adhesive and can include
the effects of plasticizers, tackifiers, base polymer, and other
additives. Typically the additives should not exceed about 50% by
weight of the total adhesive formulation.
[0061] The hot melt adhesive compositions may be formulated using
techniques known in the art. For example, the polyester,
tackifiers, plasticizers, waxes, nucleators, and other additives
can be mixed as a melt in a jacketed mixing kettle, preferably in a
jacketed heavy duty mixer. Mixing and heating can be continued
until a smooth, homogeneous mass is obtained and the remainder of
the compound is thoroughly and uniformly admixed therewith.
Formulation can be performed using equipment well known in the art
including batch mixers, Banbury mixers, kneaders, twin and single
screw continuous compounders, roll mills, and high shear mixers
(Z-blade or sigma blade). Compounding can be performed in either
air or inert gas. The adhesive can be dried before application, if
preferred, but is usually not necessary.
[0062] Ring and ball softening points are not critical for the
adhesive of the present invention and are typically above about
60.degree. C. The compatibility and wetting characteristics of the
adhesive on the substrate can depend partly on the difference in
surface tensions of the adhesive and substrate. For example, the
surface tension of the adhesive composition can be less than that
of the substrate. In another embodiment, the surface tension of the
adhesive composition is within about 5 dynes/cm of the substrate.
In yet another example, the surface tension is within about 3
dynes/cm of the substrate. If 2 different substrates are involved
such as, for example, a label and container, then the adhesive can
have a surface tension that is less than both substrates or,
alternatively, within about 5 dynes/cm of both substrates. Multiple
adhesives also can be used for gluing multiple substrates through
multiple adhesive applicators.
[0063] The hot-melt adhesive compositions of the invention may be
used to bond a wide range of substrates in addition to polyester
labels, films, and containers. For example, the adhesive
composition may be used on films prepared from polystyrene,
polyolefin, polyvinyl chloride, nylon, polycarbonate,
styrene-acrylonitrile, acrylonitrile-butadiene-styrene polymer,
styrene-butadiene copolymers, acrylics, polysulfones,
polyethersulfones, blends of the above polymers, and the like. In
another example, the adhesive compositions can be used to adhere
labels to glass, plastic, and metal containers. Representative
examples plastic containers include those made from polyesters
(such as poly(ethylene) terephthalate, "PET"), polycarbonate,
polyethylene, polypropylene, polystyrene, and nylons.
[0064] Another aspect of our invention, therefore, is a container,
comprising a label adhered thereto with a hot-melt adhesive
composition, comprising [0065] A. about 50 to 100 weight percent,
based on the total weight of the adhesive composition, of at least
one polyester, comprising (i) diacid residues, comprising about 30
to 60 mole percent, based on the total moles of diacid residues, of
the residues of adipic acid, glutaric acid, or a combination
thereof, about 30 to about 60 mole percent of the residues of
terephthalic acid, and about 0 to about 40 mole percent of at least
one modifying dicarboxylic acid having about 4 to about 40 carbon
atoms; and (ii) diol residues, comprising about 80 to about 100
mole percent, based on the total moles of diol residues, of the
residues of 1,4-butanediol, 1,6-hexanediol, or a combination
thereof; and about 0 to about 20 mole percent of the residues of at
least one modifying diol; and [0066] B. 0 to about 50 weight
percent of a tackifier, plasticizer, wax, nucleator, or combination
thereof; [0067] wherein the polyester has an inherent viscosity of
about 0.1 to about 0.35 dL/g as measured at 25.degree. C. using 0.5
grams of polymer per 100 ml of a solvent comprising 60 weight
percent phenol and 40 weight % tetrachloroethane, a melt
temperature of about 70 to about 130.degree. C., and a heat of
melting of about 0.1 cal/g to about 6 cal/g; and [0068] wherein the
adhesive composition has a melt viscosity of about 300 to about
3000 centipoise at 150.degree. C.
[0069] The above adhesive composition is understood to include the
various embodiments of the polyester, inherent viscosity, heat of
melting, plasticizers, waxes, nucleators, and tackifiers described
hereinabove in any combination. For example, the modifying
dicarboxylic acid can comprise succinic acid, suberic acid, pimelic
acid, fumaric acid, maleic acid, itaconic acid, glycolic acid
sebacic acid, azelaic acid, dimer acid, isophthalic acid,
1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid,
or combinations thereof; and the modifying diol can comprise
1,4-cyclohexanedimethanol, ethylene glycol, 1,2-propanediol,
1,3-propanediol, 1,5-pentanediol, neopentyl glycol, diethylene
glycol, triethylene glycol, 1,8-octanediol,
2,2,4-trimethyl-1,3-pentanediol, polyethylene glycol, polypropylene
glycol, 2,4-dimethyl-2-ethylhexane-1,3-diol;
2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol,
2-ethyl-2-isobutyl-1,3-propanediol; 1,3-butanediol,
1,5-pentanediol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, or
combinations thereof.
[0070] In another example, the hot-melt adhesive composition can
comprise a polyester comprising about 30 about to about 60 mole
percent of the residues of adipic acid, about 30 to about 50 mole
percent of the residues of terephthalic acid, and 0 to about 30
mole percent of the residues of a modifying dicarboxylic acid
comprising isophthalic acid; and diol residues comprising about 90
to 100 mole percent of the residues of 1,4-butanediol, and 0 to
about 10 mole percent of the residues of the modifying diol
comprise diethylene glycol, 1,4-cyclohexanedimethanol, or a
combination thereof. In another example, the diol residues comprise
about 100 mole percent of the residues of 1,6-hexanediol.
[0071] In a further example, the diacid residues can comprise about
40 to about 60 mole percent of the residues of adipic acid, about
30 to about 45 mole percent of the residues of terephthalic acid,
and about 5 to about 30 mole percent of the residues of a modifying
dicarboxylic acid; and the diol residues can comprise about 90 to
100 mole percent of the residues of 1,4-butanediol and about 10 to
0 mole percent of the residues of 1,4-cyclohexanedimethanol.
Isophthalic acid is one example of a modifying acid in the above
example.
[0072] The polyester of the hot-melt adhesive can have an inherent
viscosity of about 0.1 to about 0.35 dL/g as described hereinabove.
Some additional examples of inherent viscosities for the polyester
are about 0.1 to about 0.33; about 0.1 to about 0.30; about 0.1 to
about 0.27; about 0.1 to about 0.25; and about 0.1 to about 0.20.
In order to achieve this relatively low viscosity, the molecular
weight of the polyester, typically, will be in the range of about
1000 to about 15,000 g/mole. Some additional examples of molecular
weight ranges of the polyester are about 1000 to about 13,000
g/mole, about 1000 to about 10,000 g/mole; and about 1000 to about
8000 g/mole.
[0073] In addition, the polyester typically will have a melting
temperature of about 70 to about 130.degree. C. Other examples of
melting temperatures are about 80 to about 130.degree. C., about 80
to about 120.degree. C., about 90 to about 120.degree. C., and
about 100 to about 120.degree. C. The polyester, as noted
previously, has a heat of melting of about 0.1 cal/g to about 6
cal/g. Other examples of heat of melting ranges are ranges are
about 0.1 to about 4 cal/g, about 0.3 to about 4 cal/g, and about
0.5 and 3 cal/g. Also, as described previously, the adhesive
composition can comprise from 0 to 50 weight percent of a
tackifier, plasticizer, wax, nucleator, or combination thereof. For
example, in one embodiment, the tackifier can comprise a tall oil
rosin, gum rosin, wood rosin, hydrogenated rosin, polymerized
rosin, disproportionated rosin, aromatic hydrocarbon resin,
coumarone-indene resin, polyterpene, terpene-phenolic resin,
phenolic resin, maleic resin, ketone resin, polyester resin, or
combinations thereof. The hydrocarbon resins can be hydrogenated or
partially hydrogenated. In one embodiment, the adhesive comprises a
tackifier comprising at least one hydrogenated rosin having an acid
number of about 145 to about 175 mg KOH/gram of rosin.
[0074] Examples of plasticizers include benzoate esters, phthalate
esters, citrate esters, phosphate esters, terephthalate esters,
isophthalate esters, or a combinations thereof. For example, the
adhesive composition can comprise benzoate esters such as
1,4-cyclohexanedimethanol dibenzoate, neopentyl glycol dibenzoate,
dipropylene glycol dibenzoate, propylene glycol dibenzoate,
isodecyl benzoate, alkyl benzoate esters, or combinations
thereof.
[0075] Representative examples of some waxes that can be used in
the adhesive composition include 12-hydroxystearamide, N-(2-hydroxy
ethyl)-12-hydroxystearamide, stearamide, glycerin monostearate,
sorbitan monostearate, and 12-hydroxy stearic acid. Representative
examples of nucleators include, but are not limited to, low
molecular weight polyolefins or olefinic ionomers with melting
temperature ranging from about 70.degree. C. to 130.degree. C., or
a combination thereof. For example, in one embodiment, our
inventive adhesive composition can comprise a tackifier comprising
at least one hydrogenated rosin having an acid number of about 145
to about 175 mg KOH/gram of rosin; a plasticizer comprising
1,4-cyclohexanedimethanol dibenzoate, neopentyl glycol dibenzoate,
dipropylene glycol dibenzoate, propylene glycol dibenzoate,
isodecyl benzoate, alkyl benzoate esters having 7 to 40 carbon
atoms, or combinations thereof; and a nucleator comprising
polyethylene, polypropylene, olefinic ionomers, or combinations
thereof. In another embodiment, the adhesive composition can
comprise about 50 to about 70 weight percent of a polyester as set
forth above, about 20 to about 40 weight percent of a hydrogenated
rosin, and about 5 to about 15 weight percent of a plasticizer
comprising 1,4-cyclohexanedimethanol dibenzoate; a wax comprising
stearamide, 12-hydroxystearamide, N-(2-hydroxy
ethyl)-12-hydroxystearamide, or a combination thereof; or a
combination of the plasticizer and wax.
[0076] In another embodiment, the hot-melt adhesive composition of
the container can comprise a tackifier comprising at least one
hydrogenated rosin having an acid number of about 145 to about 160
mg KOH/gram of rosin; a plasticizer comprising
1,4-cyclohexanedimethanol dibenzoate, neopentyl glycol dibenzoate,
dipropylene glycol dibenzoate, propylene glycol dibenzoate,
isodecyl benzoate, alkyl benzoate esters having 7 to 40 carbon
atoms, or combinations thereof; and a nucleator comprising
polyethylene, polypropylene, olefinic ionomers, or combinations
thereof. In yet another example, the adhesive composition of the
container can comprise about 50 to about 70 weight percent of the
polyester, about 20 to about 40 weight percent of a hydrogenated
rosin; and about 5 to about 15 weight percent of a plasticizer
comprising 1,4-cyclohexanedimethanol dibenzoate or a wax comprising
stearamide, 12-hydroxystearamide, N-(2-hydroxy
ethyl)-12-hydroxystearamide or a combination thereof; or a
combination of the plasticizer and wax.
[0077] The container comprises a label adhered to the container
with the hot-melt adhesive described above. The label can have at
least one layer and can be prepared from a variety of materials
such as, for example, polyester, polyolefin, polyvinylchloride,
nylon, polylactic acid, paper, metal, polycarbonate, acrylic, or
polystyrene film. For example, the label can be a shrink label. In
addition, the label can be monolayer or multilayer, coextruded,
laminated, clear, opaque, pigmented, metallized, perforated,
printed, or have any other typical modification well known in the
art. For multilayer labels, the individual layers can comprise 2 or
more different polymers such as, for example, polyester with
polystyrene, polyester with polypropylene, and polystyrene with
polypropylene. Similarly, the layers can be produced by blending
one or more materials together and also can include blending
multiple polyesters together to achieve a certain shrink
performance. The film can also be microvoided or foamed to reduce
density and improve recyclability, and these in turn, can be
monolayer or multilayer with the voided layers on the inside,
outside or any combination thereof. Additives, pigments, dyes,
antiblocks, slips, lubricants, pinning additives, antistats, UV
absorbers, scavengers, and other processing aids/additives known in
the art can also be added to the film although care is required to
insure that these additives do not interfere with the performance
of the hot-melt adhesive. There is no limit on the film thickness,
although the range is typically between about 10 and 100 microns
for RAS labels.
[0078] The hot-melt adhesive is particularly useful for adhering
and seaming roll-applied, shrink labels prepared from polyester
films. These polyester labels can be attached to variety of
containers such as, for example, bottles, jars, cans, boxes, and
battery casings. The container can be of any material such as, for
example, plastics such as polyester, polyethylene, polypropylene,
nylon, polycarbonate, polystyrene, styrene-acrylonitrile,
acrylonitrile-butadiene-styrene polymer, styrene-butadiene
copolymers, acrylics, polysulfones, polyethersulfones, blends of
the above polymers, and the like; metal, glass, or combinations of
any of these materials.
[0079] For example, the container can be a poly(ethylene)
terephthalate ("PET") bottle or jar with a polyester shrink label.
This combination is convenient for recycling of polyester polymers.
Because the polyester-based, hot-melt adhesive is compatible with
PET, any adhesive residue that gets carried through with PET
recycle flake will not cause contamination or haze problems.
Generally, the adhesive will mix and transesterify with the PET
during subsequent reprocessing and have little or no negative
effect.
[0080] The polyester label can comprise a single polyester or a
blend of 2 or more polyesters. For example, the polyester or
polyester blend can comprise about 80 to 100 mole percent, based on
the total diacid residues, of the residues of terephthalic acid and
0 to 20 mole percent of one or more modifying acids that include,
but are not limited to, isophthalic acid, malonic acid, succinic
acid, glutaric acid, 1,3-cyclohexanedicarboxylic acid,
1,4-cyclohexanedicarboxylic acid, adipic acid, suberic acid,
sebacic acid, azelaic acid, dimer acid, dodecanedioic acid,
sulfoisophthalic acid, 2,6-decahydronaphthalenedicarboxylic acid,
4,4'-biphenyldicarboxylic, 3,3'- and 4,4-stilbenedicarboxylic acid,
4,4'-dibenzyldicarboxylic acid, and 1,4-, 1,5-, 2,3-, 2,6, and
2,7-naphthalenedicarboxylic acid. The diol residues can comprise 60
to 99 mole percent of ethylene glycol with 1 to 40 mole percent of
one or more modifying glycols that include, but are not limited to,
1,4 cyclohexanedimethanol, diethylene glycol propylene glycol,
1,3-propanediol, 2,4-dimethyl2-ethylhexane1,3-diol,
2,2-dimethyl-1,3-propanediol, diethylene glycol,
1,4-cyclohexanedimethanol, 2-ethyl-2-butyl-1,3-propanediol,
2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol,
neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol,
2,2,4-trimethyl-1,6-hexanediol, thiodiethanol,
1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol,
2,2,4,4-tetramethyl-1,3-cyclobutanediol and the like.
[0081] In another example, the polyester or polyester blend can
comprise about 90 to 100 mole percent, based on the total diacid
residues, of the residues of terephthalic acid. In another example,
the diacid residues of the polyester label may comprise about 95 to
100 mole percent of the residues of terephthalic acid. Some
additional examples of terephthalic acid residue content in the
polyester label are greater than about 90 mole percent, about 92
mole percent, about 95 mole percent, about 97 mole percent, and
about 99 mole percent. The diacid residues of the polyester label
may further comprise up to about 10 mole percent of the residues of
a modifying carboxylic acid containing 4 to 40 carbon atoms if
desired. For example, from 0 to about 10 mole percent of other
aromatic dicarboxylic acids containing 8 to about 16 carbon atoms,
cycloaliphatic dicarboxylic acids containing 8 to about 16 carbon
atoms, acyclic dicarboxylic acids containing about 2 to about 16
carbon atoms, or mixtures thereof may be used. Examples of
modifying dicarboxylic acids include, but are not limited to,
malonic acid, succinic acid, glutaric acid,
1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid,
adipic acid, suberic acid, sebacic acid, azelaic acid, dimer acid,
dodecanedioic acid, sulfoisophthalic acid,
2,6-decahydronaphthalenedicarboxylic acid, isophthalic acid,
4,4'-biphenyldicarboxylic, 3,3'- and 4,4-stilbenedicarboxylic acid,
4,4'-dibenzyldicarboxylic acid, and 1,4-, 1,5-, 2,3-, 2,6, and
2,7-naphthalenedicarboxylic acid. Where cis and trans isomers are
possible, the pure cis or trans or a mixture of cis and trans
isomers may be used.
[0082] The polyester label also comprises diol residues that
comprise about 5 to about 89 mole percent, based on the total
polyester diol residues, of the residues of ethylene glycol, about
10 to about 70 mole percent of the residues of
1,4-cyclohexanedimethanol, and about 1 to about 25 mole percent of
the residues of diethylene glycol. The polyester may also comprise
from 0 to about 10 mole percent of at least one modifying diol.
Some representative examples of modifying diols are as listed above
and include propylene glycol, 1,3-propanediol,
2,4-dimethyl-2-ethylhexane1,3-diol, 2,2-dimethyl-1,3-propanediol,
diethylene glycol, 1,4-cyclohexanedimethanol,
2-ethyl-2-butyl-1,3-propanediol,
2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol,
neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol,
2,2,4-trimethyl-1,6-hexanediol, thiodiethanol,
1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol,
2,2,4,4-tetramethyl-1,3-cyclobutanediol and the like.
[0083] For example, the polyester label may comprise about 95 to
100 mole percent terephthalic acid residues, about 35 to about 89
mole percent ethylene glycol residues, and about 10 to about 40
mole percent 1,4-cyclohexanedimethanol residues, and about 1 to
about 25 mole percent diethylene glycol residues. In another
example, the polyester label can comprise about 50 to about 77 mole
percent ethylene glycol residues, about 15 to about 35 mole percent
1,4-cyclohexanedimethanol residues, and about 8 to about 15 mole
percent diethylene glycol residues. In yet another example, the
polyester label can comprise about 90 to about 100 mole percent of
the residues of terephthalic acid and about 52 to about 88 mole
percent of the residues of ethylene glycol, about 10 to about 28
mole percent of the residues of 1,4-cyclohexanedimethanol, and
about 2 to about 20 mole percent of the residues of diethylene
glycol. Other possible combinations of mole percentage ranges for
the terephthalic acid, ethylene glycol, 1,4-cyclohexanedimethanol,
and diethylene glycol residues will be apparent to persons skilled
in the art.
[0084] The polyester shrink labels used on the container of the
invention, typically, are prepared by methods well-known to persons
skilled in the art such as, for example, extrusion, calendering,
casting, drafting, tentering, or blowing. These methods initially
create an unoriented or "cast" film that is subsequently stretched
in at least one direction to impart orientation. The term
"oriented", as used herein, means that the polyester film is
stretched to impart direction or orientation in the polymer chains.
The polyester film, thus, may be "uniaxially stretched", meaning
the polymer matrix is stretched in one direction or "biaxially
stretched," meaning the polymer matrix has been stretched in two
different directions. Typically, but not always, the two directions
are substantially perpendicular. For example, in the case of a
film, the two directions are in the longitudinal or machine
direction ("MD") of the film (the direction in which the film is
produced on a film-making machine) and the transverse direction
("TD") of the film (the direction perpendicular to the MD of the
film). Biaxially stretched articles may be sequentially stretched,
simultaneously stretched, or stretched by some combination of
simultaneous and sequential stretching. In generally, stretch or
draw ratios of about 1.1.times. to about 8.times. are imparted in
one or more directions to create uniaxially or biaxially oriented
films. The phrases "stretch ratio" and "draw ratio", are intended
to be synonymous and refer to the length of the stretched film
divided by the length of the unstretched film. For example,
"machine direction draw ratio" or "MD draw ratio" refers to the
draw ratio in the machine direction. Similarly, "TD draw ratio"
refers to the draw ratio in the transverse direction. More
typically, stretch ratios are from 4.times. to about 6.times.. The
stretching can be performed, for example, using a double-bubble
blown film tower, a tenter frame, a machine direction drafter, the
drafting and drawdown section of a calendering line, or combination
of these methods. Stretching is generally performed at or near the
glass transition temperature (Tg) of the polymer. For polyesters,
for example, this range is typically Tg+5.degree. C. (Tg+10.degree.
F.) to about Tg+33.degree. C. (Tg+60.degree. F.), although the
range may vary slightly depending on additives. A lower stretch
temperature will impart more orientation with less relaxation (and
hence more shrinkage), but may increase film tearing. To balance
these effects, an optimum temperature in the mid-range is often
chosen.
[0085] For example, the label may be prepared from a
heat-shrinkable, polyester film that is stretched in the machine
direction (MD) at a draw ratio of about 2 to about 7; about 2 to
about 6; about 3 to about 7; about 3 to about 6; about 4 to about
7; or about 4 to about 6. Typically, in stretching the film, it may
be initially heated to a temperature above its glass transition
temperature. The film then may be stretched at of rate of about 10
to 300 meters per minute.
[0086] The polyester, heat-shrinkable film used in the label may be
uniaxially oriented, meaning that the processing history may
include stretching in the machine direction without stretching in
the transverse direction. Alternatively, the heat-shrinkable film
processing history may include additional stretching, either
simultaneously or sequentially, in the transverse direction at a
draw ratio of less than about 1.1, about 1.2, about 1.5, or about
2.0. For example, the heat-shrinkable film may be stretched in the
machine direction at a draw ratio of about 2 to about 6 and in the
transverse direction at a draw ratio of about 1.2 to about 1.6.
[0087] Post-stretch annealing or heat setting may be used to adjust
shrink properties of the film, although annealing the film under
tension can cause an increase in TD growth due to additional
neck-in. The term "neck-in" refers to the decrease in width
experienced by a web as it is stretched in the machine direction.
Annealing times and temperatures will vary from machine to machine
and with each formulation, but typically will range from about Tg
to about Tg+50.degree. C. for about 1 to about 15 seconds. Higher
temperatures usually require shorter annealing times and are
preferred for higher line speeds. The annealing process typically
will reduce the MD shrinkage accordingly. Generally, to avoid
additional neck-in and TD growth, annealing should be carried out
while the film is under low tension. For example, in one
embodiment, annealing is carried out under conditions that maintain
post-stretch, total neck-in of the film web to 5% or less.
[0088] In one embodiment, the label comprises a machine direction
(MD) oriented polyester film having an ultimate shrinkage of 20% or
greater, preferably 40% or greater. In another embodiment, the film
should have an off-axis shrinkage or growth (TD direction) of less
than 10%. The phrase "TD growth or shrinkage", as used herein, is
intended to mean TD growth or shrinkage as measured the drive side,
center, or operator side of the film web from which the label is
cut. For example, if any section of film exhibits TD growth or
shrinkage exceeding about 10%, then that film would be considered
to have a TD growth or shrinkage greater than 10%, even if other
sections of the film web exhibited less than 10% growth or
shrinkage. The film can be produced by any standard film process
including simultaneous or sequential biaxial stretching, drafting,
tentering, calendering, or blown film (single or double bubble).
Typically, the polyester films described herein film will normally
have a shrink onset temperature between 60 and 80.degree. C.
[0089] For example, in one embodiment, the label can comprise a
biaxially oriented film in which the heat-shrinkable film undergoes
from about 25 to about 85 percent machine direction (MD) shrinkage
and less than about 10% off-axis (TD) shrinkage shrinkage or growth
when immersed in 95.degree. C. water for 10 seconds. Films with
these properties can be produced by (i) stretching in the machine
direction (MD) at a draw ratio of about 3 to about 6 at a
temperature above the glass transition temperature, (ii) stretching
in the transverse direction (TD) at a draw ratio of about 1.1 to
about 3, and (iii) annealing the film in the heatset portion of the
tenter frame at a temperature between about 80 and 180.degree.
C.
[0090] In another embodiment, the label adhered to the container of
the invention can have about 25 to about 85 percent machine
direction shrinkage and about 0 to about 10 percent transverse
direction shrinkage or growth when immersed in water at 95.degree.
C. for 10 seconds. Some additional examples of MD shrinkage that
can characterize the heat-shrinkable label include about 25 to
about 80%; about 25 to about 75%; about 25 to about 70%; about 25
to about 65%; about 25 to about 60%; about 25 to about 50%; about
25 to about 45%; about 25 to about 40%; about 30 to about 85%;
about 30 to about 80%; about 30 to about 75%; about 30 to about
70%; about 30 to about 65%; about 30 to about 60%; about 30 to
about 55%; about 30 to about 50%; about 35 to about 85%; about 35
to about 80%; about 35 to about 75%; about 35 to about 70%; about
35 to about 65%; about 35 to about 60%; about 35 to about 55%;
about 35 to about 50%; about 40 to about 85%; about 40 to about
80%; about 40 to about 75%; about 40 to about 70%; about 40 to
about 65%; about 40 to about 60%; about 40 to about 55%; about 40
to about 50%; about 45 to about 85%; about 45 to about 80%; about
45 to about 75%; about 45 to about 70%; about 45 to about 65%;
about 45 to about 60%; about 45 to about 55%; about 50 to about
85%; about 50 to about 80%; about 50 to about 75%; about 50 to
about 70%; about or 50 to about 60%. In addition, the
heat-shrinkable label may have about 0 to about 4, 0 to about 5, 0
to about 6, 0 to about 7, 0 to about 8, or 0 to about 10 percent
transverse direction shrinkage or growth.
[0091] The polyester label also may further comprise a voiding
agent, comprising at least one polymer incompatible with the
polyester film and dispersed therein. The terms "voids",
"microvoids", and "micropores", as used herein, are intended to be
synonymous and are well-understood by persons skilled in the art to
mean tiny, discrete voids or pores contained within the polyester
below the surface of the polyester film of the label that are
intentionally created during the manufacture of the article.
Similarly, the terms "voided", "microvoided", "cavitated" and
"void-containing", as used herein in reference to the polyester
label, are intended to be synonymous and mean "containing tiny,
discrete voids or pores". The labels of the invention include a
"voiding agent" dispersed within the polyester matrix. The term
"voiding agent", as used herein, is synonomous with the terms
"voiding composition", "microvoiding agent", and "cavitation agent"
and is understood to mean a substance dispersed within a polymer
matrix that is useful to bring about or cause the formation voids
within the polymer matrix" upon orientation or stretching of the
polymer matrix. The term "polymer matrix", as used herein, is
synonymous with the term "matrix polymer" and refers to the
polyester or polyester blend that provides a continuous phase in
which the voiding again may be dispersed such that the particles of
the voiding agent are surrounded and contained by the continuous
phase.
[0092] Typical voiding agents which may be used include at least
one polymer selected from cellulosic polymers, starch, esterified
starch, polyketones, polyester, polyamides, polysulfones,
polyimides, polycarbonates, olefinic polymers, and copolymers
thereof. The term "olefinic polymer", as used herein is intended to
mean a polymer resulting from the addition polymerization of
ethylenically unsaturated monomers such as, for example,
polyethylene, polypropylene, polystyrene, poly(acrylonitrile),
poly(acrylamide), acrylic polymers, poly(vinyl acetate), poly(vinyl
chloride), and copolymers of these polymers. The voiding agent may
also comprise one or more inorganic compounds such as, for example
talc, silicon dioxide, titanium dioxide, calcium carbonate, barium
sulfate, kaolin, wollastonite, and mica. The voiding agent also may
comprise a combination of polymeric and inorganic materials. The
polyester film forms voids on orientation or stretching at a
temperature at or above the Tg of the polyester matrix. Stretching
may be carried out in one or more directions at a stretch or draw
ratio of at least 1.5. Thus, as described previously, the
composition may be "uniaxially stretched", meaning the polyester is
stretched in one direction or "biaxially stretched," meaning the
polyester is stretched in two different directions.
[0093] The voiding agent may comprise one or more polymers. The
voiding agent may be a single polymer or blend of one or more
polymers. For example, the voiding agent may comprise at least one
polymer selected from cellulosic polymers, starch, esterified
starch, polyketones, fluoropolymers, polyacetals, polyesters,
polyamides, polysulfones, polyimides, polycarbonates, olefinic
polymers, and copolymers of these polymers with other monomers such
as, for example, copolymers of ethylene with acrylic acid and its
esters. Cellulosic polymers are particularly efficient voiding
agents. For example, the voiding agent may comprise a first polymer
comprising at least one cellulosic polymer comprising one or more
of microcrystalline cellulose, a cellulose ester, or a cellulose
ether. In another example, the first polymer may be a cellulose
ester such as, for example, cellulose acetate, cellulose
triacetate, cellulose acetate propionate, or cellulose acetate
butyrate. In yet another example, the first polymer may be a
cellulose ether which may include, but is not limited to, one or
more of hydroxypropyl cellulose, methyl ethyl cellulose, or
carboxymethyl cellulose.
[0094] The voiding agent also may comprise a second polymer
comprising one or more polymers selected from polyamides,
polyketones, polysulfones, fluoropolymers, polyacetals, polyesters,
polycarbonates, olefinic polymers, or copolymers thereof. For
example, the second polymer may include, but is not limited to, one
or more olefinic polymers such as, for example, polyethylene,
polystyrene, polypropylene, and copolymers thereof. Further
non-limiting examples of olefinic copolymers include ethylene vinyl
acetate, ethylene vinyl alcohol copolymer, ethylene methyl acrylate
copolymer, ethylene butyl acrylate copolymer, ethylene acrylic acid
copolymer, ionomer, or mixtures thereof. Olefinic copolymers such
as, for example, ethylene methyl acrylate copolymer (abbreviated
herein as "EMAC"), ethylene butyl acrylate (abbreviated herein as
"EBAC"), ethylene acrylic acid (abbreviated herein as "EAA")
copolymer, maleated, oxidized or carboxylated PE, and ionomers may
be used advantageously with the cellulosic polymers described above
as the second polymer to increase the opacity and improve the
overall aesthetics and feel of the film. These olefinic polymers
also may aid the compounding and dispersion of the cellulosic.
Thus, for example, the second polymer may comprise one or more of
EMAC or EBAC. In another embodiment, for example, the voiding agent
can comprise a first polymer comprising cellulose acetate,
cellulose triacetate, cellulose acetate proprionate, cellulose
acetate butyrate, hydroxypropyl cellulose, methyl ethyl cellulose,
carboxymethyl cellulose, or mixtures thereof; and a second polymer
comprising polyethylene, polystyrene, polypropylene, ethylene vinyl
acetate, ethylene vinyl alcohol copolymer, ethylene methyl acrylate
copolymer, ethylene butyl acrylate copolymer, ethylene acrylic acid
copolymer, ionomer, or mixtures thereof. In another example, the
first polymer may comprise one or more of cellulose acetate or
cellulose acetate propionate and the second polymer may comprise
polystyrene, polypropylene, ethylene methyl acrylate copolymer, or
a mixture thereof. In yet another example, the first polymer
comprises cellulose acetate, the second polymer comprises
polypropylene and ethylene methyl acrylate copolymer.
[0095] The polymers that may be used as the first polymer or second
polymer, of the voiding agent may be prepared according to methods
well-known in the art or obtained commercially. Examples of
commercially available polymers which may be used in the invention
include EASTAR.TM., EASTAPAK.TM., SPECTAR.TM., and EMBRACE.TM.
polyesters and copolyesters available from Eastman Chemical Co.;
LUCITE.TM. acrylics available from Dupont; TENITE.TM. cellulose
esters available from Eastman Chemical Co.; LEXAN.TM. (available
from Sabic Innovative Plastics) or MAKROLON.TM. (available from
Bayer) polycarbonates; DELRIN.TM. polyacetals available from
Dupont; K-RESIN.TM. (available from Phillips) and
FINACLEAR.TM./FINACRYSTA.TM. (available from Atofina) styrenics and
styrenic copolymers; FINATHENE.TM. (available from Atofina) and
HIFOR.TM./TENITE.TM. (available from Eastman) polyethylenes;
ZYTE.TM. nylons available from Dupont; ULTRAPEK.TM.PEEK available
from BASF; KAPTON.TM. polyimides available from Dupont; and
TEDLAR.TM. and KYNAR.TM. fluoropolymers available from Dupont and
Atofina, respectively.
[0096] The void-containing, polyester label will generally contain
about 1 to about 40 weight percent of voiding agent, based on the
total weight of the film. Other examples of voiding agent content
within the film are about 5 to about 35 weight percent, about 10 to
about 35 weight percent, about 15 to about 35 weight percent, and
about 15 to about 30 weight percent. Typically, the voiding agent
comprises about 5 to about 95 weight percent of the first polymer,
based on the total weight of the voiding agent. Other weight
percent ranges for the first polymer within the voiding agent are
about 30 to about 60 weight percent and about 50 to about 60 weight
percent. When the voiding agent comprises a cellulosic polymer and
an olefinic polymer, the voiding agent typically will comprise at
least 5 weight percent or more of the cellulosic polymer, based on
the total weight of the composition. For example, the voiding agent
may comprise at least 30 weight percent of the cellulosic polymer.
The components of the voiding agent may be compounded together on a
mixing device such as, for example, a twin screw extruder,
planetary mixer, or Banbury mixer, or the components may be added
separately during film formation. Small amounts of inorganic
voiding agents may also be included. It may be desirable to
precompound the cellulosic polymer and the olefin, in which the
olefin may be used as part of the carrier resin in which the
cellulosic is dispersed. Precompounding the olefin and the
cellulosic polymer provides the added advantage that the olefin
serves as a vehicle for dispersing the cellulosic polymer, and
provides an efficient moisture barrier to prevent uptake of
moisture into the cellulosic polymer prior to final extrusion. In
addition, the voiding agent is easier to handle and dry. It is also
possible to use blends of polymers as voiding agents as long as
sufficient shearing, for example, by the use of a twin screw or
high shear single screw extruder, is used to adequately disperse
the components of the voiding agent.
[0097] As noted above, the hot-melt adhesive composition of the
invention can be used for adhering roll-on, shrink labels to a
container. Our invention, therefore, also includes a process for
applying a roll-on, shrink label to a container, comprising: [0098]
I. applying a hot-melt adhesive to one or more locations on a
heat-shrinkable label, a container, or a combination thereof,
wherein the hot-melt adhesive comprises [0099] A. about 50 to 100
weight percent, based on the total weight of the adhesive
composition, of at least one polyester, comprising (i) diacid
residues, comprising about 30 to 60 mole percent, based on the
total moles of diacid residues, of the residues of adipic acid,
glutaric acid, or a combination thereof, about 30 to about 60 mole
percent of the residues of terephthalic acid, and about 0 to about
40 mole percent of at least one modifying dicarboxylic acid having
about 4 to about 40 carbon atoms; and (ii) diol residues,
comprising about 80 to about 100 mole percent, based on the total
moles of diol residues, of the residues of 1,4-butanediol,
1,6-hexanediol, or a combination thereof; and about 0 to about 20
mole percent of the residues of at least one modifying diol; and
[0100] B. 0 to about 50 weight percent of a tackifier, plasticizer,
wax, nucleator, or combination thereof; [0101] wherein the
polyester has an inherent viscosity of about 0.1 to about 0.35 dL/g
as measured at 25.degree. C. using 0.5 grams of polymer per 100 ml
of a solvent comprising 60 weight percent phenol and 40 weight %
tetrachloroethane, a melting temperature of about 70 to about
130.degree. C., and a heat of melting of about 0.1 cal/g to about 6
cal/g; and [0102] wherein the adhesive composition has a melt
viscosity of about 300 to about 3000 centipoise at 150.degree. C.;
[0103] II. affixing the label around the container to produce a
labeled container; [0104] III. allowing the applied hot-melt
adhesive to at least partially crystallize; and [0105] IV.
shrinking the label by exposing the labeled container to heat. The
above process is understood to include the various embodiments
described hereinabove for the hot-melt adhesive composition such
as, for example, the various embodiments of the polyester, inherent
viscosity, heat of melting, plasticizers, waxes, nucleators, and
tackifiers in any combination; the container; and the polyester
label. For example, the hot-melt adhesive composition can comprise
a polyester comprising diacid residues comprising about 30 about to
about 60 mole percent of the residues of adipic acid, about 30 to
about 50 mole percent of the residues of terephthalic acid, and 0
to about 30 mole percent of the residues of isophthalic acid; and
diol residues comprising about 80 to 100 mole percent of the
residues of 1,4-butanediol, and 0 to about 10 mole percent of the
residues of diethylene glycol, 1,4-cyclohexanedimethanol, or a
combination thereof. In another example, the diol residues can
comprise about 100 mole percent of the residues of
1,6-hexanediol.
[0106] The hot-melt adhesive can be used to affix the heat shrink
labels to the appropriate containers using conventional packaging
equipment, as described, for example, in U.S. Pat. Nos. 4,704,173
and 4,844,957. These techniques are particularly useful in the
labeling of glass, metal or plastic, cylindrical or multi-faceted
containers and can be used for labels prepared from polyesters,
polyolefins such as polypropylene or polyethylene, polyvinyl
chloride films, or similar plastic sheets.
[0107] The hot-melt adhesive can be applied to one or more
locations on the heat-shrinkable label by any method known in the
art including wipe-on, spray, roller, nozzle, foamed hot melt
applicator, high and low pressure applicator, gravure, adhesive
gun, wheel, pattern coater, and the like. For example, the hot-melt
adhesive can be applied to one or both ends of the label and on one
or more surfaces. Alternatively, the adhesive can be applied to one
surface of the label and on the container. Other applications can
include any method for applying the adhesive to one of two
substrates, after which the two are immediately brought together to
form an adhesive bond. For example, the label can have the hot melt
adhesive applied thereto in a generally vertical line at the
leading and trailing edges of the label. The balance of the label
is preferably free of adhesive so that the label can shift as it
shrinks without causing wrinkling of the label material.
Alternately, applications where the hot melt is applied to a
substrate via an extrusion coater, doctor blade, slot die coater,
and the like, and then laminated to another substrate later via
heat activation can be envisioned. The adhesive can be applied at
any thickness, with or without a primer, liner or release coating.
The adhesive also can be applied in conjunction with other seaming
methods. For example, the hot melt adhesive can be used to tack the
label to a container for seaming using another method such as, for
example, solvent seaming, ultrasonic seaming, or laser seaming.
[0108] After applying the adhesive, the label is affixed to the
container by any method known in the art. For example, the hot-melt
adhesive may be applied to a narrow region of the container or at
the leading end of the film segment to secure the leading end of
the film to the container, the film wrapped around the container
and the film segment secured to the container by overlapping the
trailing end, a narrow region of which has been coated with the hot
melt adhesive.
[0109] During the application of the adhesive, the label may be
supported and transported by a rotary vacuum drum, or other label
transport mechanisms well known in the art. The leading end of the
label is brought into positive or compressive contact with a
container, or other article, providing an adhesive bond between the
two. The container is thereafter spun about its axis to wrap the
full extent of the label around the container.
[0110] As the trailing end of the label comes into initial contact
with the underlying leading end of the label, a compressive force
is applied to the unsupported or free standing seam portion of the
label. This force is conveniently provided by pneumatic means, such
as a jet of air directed generally outwardly from the axis of the
container against the inner wall of the unsupported seam. The wall
of the vacuum drum or other label transport apparatus provides a
convenient backing against which the pneumatic force can work.
Mechanical means, such as a wheel, a finger, or the like could also
be substituted for the air jet to apply the necessary compressive
forces against the label seam. The application of such compressive
force at the critical moment of initial contact between the leading
and trailing ends of the label, is effective to maintain the two
ends in intimate contact while the seam bond is formed.
[0111] Before application to the label, the hot-melt adhesive is
melted above the melt temperature ("T.sub.m") thereby taking it
from a crystalline solid to a liquid. Before application to the
shrink label, however, it is desirable to cool the adhesive to
reduce the temperature to below the shrink onset temperature of the
shrink label while maintaining the adhesive in liquid form.
[0112] After the label is affixed to the container, it is allowed
to at least partially crystallize before exposing the container to
heat to shrink the label. The amount of crystallization can be
adjusted, among other things, by the polyester composition, the
presence of a nucleator, the application temperature of the
hot-melt adhesive, and the duration between the application of the
adhesive and commencement of heating of the container in the shrink
oven. The adhesive once applied to the substrate will continue to
cool and will rapidly begin to crystallize and harden into a high
modulus solid. The degree of crystallization can be determined by
differential scanning calorimetry by measuring the melting
endotherm. Typically, the recrystallization temperature
("T.sub.rcry") (i.e. either the crystallization temperature that
occurs upon cooling, denoted at "T.sub.cc" or the crystallization
temperature that occurs on subsequent heating "T.sub.ch", whichever
occurs first if both are present) will be below the shrink onset
temperature, T.sub.so (if multiple recrystallization peaks are
present, then at least one should be below T.sub.so). In one
embodiment, for example, the recrystallization temperature can be
at least 20.degree. C. lower than T.sub.so.
[0113] After the hot-melt adhesive is allowed to at least partially
crystallize, the labeled container is exposed to heat to shrink the
label. The labeled container is exposed to heat typically by
passing the container through a shrink oven or tunnel at a
temperature above the shrink onset temperature of the label in
accordance with methods well-known in the art. Typical shrink
tunnels use steam, hot air, infrared heaters, or a combination of
these methods to maintain a temperature of about 80 to about
90.degree. C. A typical residence time for a container in a shrink
tunnel will range from about 2 to about 20 seconds.
[0114] In addition to the container and film materials that are
commonly used in roll-applied, shrink label applications, the
adhesive compositions of the invention also can be applied to a
number of substrates including aluminum, copper, lead, other
metals, and other metalized polymer films, paper, leather, glass,
polypropylene, polyethylene, polyvinyl chloride, polyester,
cellulosics (cellophane and cellulose acetate), polystyrene,
polyurethane, acrylic, polyimide, ultra-high molecular weight
polyethylene, polycarbonate, polyvinylalcohol, polyamide,
polylactide, styrene-acrylonitrile, acrylonitrile-butadiene-styrene
polymer, styrene-butadiene copolymers, polysulfones,
polyethersulfones, blends, foam, woven fabric, nonwoven, tissue,
and synthetic paper.
[0115] Other general application areas include case and carton
sealing, corrugated containers, tray sealing, paper laminates,
nonwovens (e.g., diapers, sanitary, incontinence, disposable
garments, filters & separators), elastic attachments,
construction adhesives, bookbinding for books and periodicals,
labels, bags, textiles, carpet seaming, furniture (including office
partitions and built in furniture), cans, tubes, drums, coated
abrasives (sand paper, sanding discs, sanding belts, grinding
wheels, etc.), automotive acoustic deadening adhesive, wax-like
coatings (water repellant), coatings for packaging, composites,
foams, membranes, sponges, primer, hot melt for polyester film to
be heat activated by the user at a later time, flexible printed
circuit film bonding, stitchless sewing, adhesives to reinforce
seams, foot wear, art and hobby, multiwall paper bags, specialty
bags, cigarette papers and filters, coextruded tie coats, peelable
tops for closures of beverage cans and foods, seam sealed or
adhesive bonded containers, inks, flux, wood products (plywood,
reconstituted wood board products, hard board, medium density fiber
board, particle board, oriented strand board), and glass laminating
adhesives.
[0116] In one embodiment, for example, the adhesive composition is
a 100% recyclable pressure sensitive adhesive comprising a
polyester adhesive and a polyester backing. In another embodiment,
the adhesives of the invention can be used as modifiers to paints
and inks. Yet another embodiment is the use of these adhesives to
produce peelable seals for lidding film and related packaging
applications.
[0117] The invention also includes the following embodiments that
are set forth below in paragraphs [0085]-[0103]: a hot-melt,
adhesive composition, comprising:
A. about 50 to 100 weight percent, based on the total weight of the
adhesive composition, of at least one polyester, comprising (i)
diacid residues, comprising about 30 to 60 mole percent, based on
the total moles of diacid residues, of the residues of adipic acid,
glutaric acid, or a combination thereof, about 30 to about 60 mole
percent of the residues of terephthalic acid, and about 0 to about
40 mole percent of at least one modifying dicarboxylic acid having
about 4 to about 40 carbon atoms; and (ii) diol residues,
comprising about 80 to about 100 mole percent, based on the total
moles of diol residues, of the residues of 1,4-butanediol,
1,6-hexanediol, or a combination thereof; and about 0 to about 20
mole percent of the residues of at least one modifying diol; and B.
0 to about 50 weight percent of a tackifier, plasticizer, wax,
nucleator, or combination thereof;
[0118] wherein the polyester has an inherent viscosity of about 0.1
to about 0.35 dL/g as measured at 25.degree. C. using 0.5 grams of
polymer per 100 ml of a solvent comprising 60 weight percent phenol
and 40 weight % tetrachloroethane, a melting temperature of about
70 to about 130.degree. C., and a heat of melting of about 0.1
cal/g to about 6 cal/g; and
[0119] wherein the adhesive composition has a melt viscosity of
about 300 to about 3000 centipoise at 150.degree. C.
[0120] The adhesive composition that includes the embodiments of
paragraph [0085], wherein the modifying dicarboxylic acid comprises
succinic acid, suberic acid, pimelic acid, fumaric acid, maleic
acid, itaconic acid, glycolic acid sebacic acid, azelaic acid,
dimer acid, isophthalic acid, 1,3-cyclohexanedicarboxylic acid,
1,4-cyclohexanedicarboxylic acid, or combinations thereof; and the
modifying diol comprises 1,4-cyclohexanedimethanol, ethylene
glycol, 1,2-propanediol, 1,3-propanediol, 1,5-pentanediol,
neopentyl glycol, diethylene glycol, triethylene glycol,
1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, polyethylene
glycol, polypropylene glycol, 2,4-dimethyl-2-ethylhexane-1,3-diol;
2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol,
2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol,
1,5-pentanediol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, or
combinations thereof.
[0121] The adhesive composition that includes the embodiments of
paragraph [0086], wherein the diacid residues comprise about 30
about to about 60 mole percent of the residues of adipic acid,
about 30 to about 50 mole percent of the residues of terephthalic
acid, and 0 to about 30 mole percent of the residues of the
modifying dicarboxylic acid; and the diol residues comprise about
90 to 100 mole percent of the residues of 1,4-butanediol, and 0 to
about 10 mole percent of the residues of the modifying diol.
[0122] The adhesive composition that includes the embodiments of
paragraph [0087], wherein the modifying dicarboxylic acid comprises
isophthalic acid; and the modifying diol comprises diethylene
glycol, 1,4-cyclohexanedimethanol, or a combination thereof.
[0123] The adhesive composition that includes the embodiments of
paragraph [0088], wherein the diacid residues comprise about 40 to
about 60 mole percent of the residues of adipic acid, about 30 to
about 45 mole percent of the residues of terephthalic acid, and
about 5 to about 30 mole percent of the residues of the modifying
dicarboxylic acid; and the modifying diol comprises
1,4-cyclohexanedimethanol.
[0124] The adhesive composition that includes the embodiments of
any one of paragraphs [0085]-[0089], wherein the tackifier
comprises a tall oil rosin, gum rosin, wood rosin, hydrogenated
rosin, polymerized rosin, disproportionated rosin, aromatic
hydrocarbon resin, coumarone-indene resin, polyterpene,
terpene-phenolic resin, phenolic resin, maleic resin, ketone resin,
polyester resin, or combinations thereof; the plasticizer comprises
a benzoate ester, phthalate ester, citrate ester, phosphate ester,
terephthalate ester, isophthalate ester, or combinations thereof;
the wax comprises stearamide, 12-hydroxystearamide, N-(2-hydroxy
ethyl)-12-hydroxystearamide, glycerin monostearate, sorbitan
monostearate, 12-hydroxy stearic acid, or combinations thereof; and
the nucleator comprises a polyolefin or olefinic ionomer having a
melting temperature of about 70 to about 130.degree. C., or a
mixture thereof.
[0125] The adhesive composition that includes the embodiments of
any one of paragraphs [0085]-[0090], wherein the tackifier
comprises at least one hydrogenated rosin having an acid number of
about 145 to about 160 mg KOH/gram of rosin; the plasticizer
comprises 1,4-cyclohexanedimethanol dibenzoate, neopentyl glycol
dibenzoate, dipropylene glycol dibenzoate, propylene glycol
dibenzoate, isodecyl benzoate, alkyl benzoate esters having 7 to 40
carbon atoms, or combinations thereof; and the nucleator comprises
polyethylene, polypropylene, olefinic ionomers, or combinations
thereof.
[0126] The adhesive composition that includes the embodiments of
any one of paragraphs [0085]-[0091], which comprises about 50 to
about 70 weight percent of the polyester, about 20 to about 40
weight percent of the hydrogenated rosin; and about 5 to about 15
weight percent of a plasticizer comprising
1,4-cyclohexanedimethanol dibenzoate or a wax comprising
stearamide, 12-hydroxystearamide, N-(2-hydroxy
ethyl)-12-hydroxystearamide or a combination thereof; or a
combination of the plasticizer and wax.
[0127] The adhesive composition that includes the embodiments of
any one of paragraphs [0085]-[0092], wherein the polyester has a
heat of melting of about 0.1 to about 4 cal/g.
[0128] The adhesive composition that includes the embodiments of
any one of paragraphs [0085]-[0093], which comprises about 0.1 to
about 5 weight percent of the nucleator.
[0129] A container, comprising a label adhered thereto with a
hot-melt adhesive composition, comprising the hot-melt adhesive
composition of any one of paragraphs [0085]-[0094]
[0130] The container that includes the embodiments of paragraph
[0095], wherein the polyester of the adhesive composition has a
heat of melting of about 0.1 to about 4 cal/g and a melting
temperature of about 90 to about 120.degree. C.
[0131] The container that includes the embodiments of paragraphs
[0095] or [0096], wherein the label has at least one layer and
comprises a polyester, polyolefin, polyvinylchloride, polylactic
acid, paper, metal, or polystyrene film.
[0132] The container that includes the embodiments of paragraphs
[0095], [0096], or [0097] wherein the label is a shrink label.
[0133] The container that includes the embodiments of any one of
paragraphs [0095]-[0098], wherein the label comprises a polyester
film comprising about 90 to about 100 mole percent of the residues
of terephthalic acid, based on the total moles of diacid residues;
and about 52 to about 88 mole percent of the residues of ethylene
glycol, based on the total moles of diol residues, about 10 to
about 28 mole percent of the residues of 1,4-cyclohexanedimethanol,
and about 2 to about 20 mole percent of the residues of diethylene
glycol.
[0134] The container that includes the embodiments of any one of
paragraphs [0095]-[0099], wherein the label has about 25 to about
85 percent machine direction shrinkage and 0 to about 10 percent
transverse direction shrinkage or growth.
[0135] The container that includes the embodiments of any one of
paragraphs [0095]-[0100], wherein the polyester label further
comprises a voiding agent, comprising at least one polymer
incompatible with the polyester film and dispersed therein.
[0136] A container that includes the embodiments of any one of
paragraphs [0095]-[0101] which is a bottle, jar, can, box, or
battery casing.
[0137] A process for applying a roll-on, shrink label to a
container, comprising: [0138] I. applying a hot-melt adhesive that
includes the embodiments of paragraphs [0085]-[0094], to one or
more locations on a heat-shrinkable label, a container, or a
combination thereof, wherein the hot-melt adhesive comprises [0139]
A. about 50 to 100 weight percent, based on the total weight of the
adhesive composition, of at least one polyester, comprising (i)
diacid residues, comprising about 30 to 60 mole percent, based on
the total moles of diacid residues, of the residues of adipic acid,
glutaric acid, or a combination thereof, about 30 to about 60 mole
percent of the residues of terephthalic acid, and about 0 to about
40 mole percent of at least one modifying dicarboxylic acid having
about 4 to about 40 carbon atoms; and (ii) diol residues,
comprising about 80 to about 100 mole percent, based on the total
moles of diol residues, of the residues of 1,4-butanediol,
1,6-hexanediol, or a combination thereof; and about 0 to about 20
mole percent of the residues of at least one modifying diol; and
[0140] B. 0 to about 50 weight percent of a tackifier, plasticizer,
wax, nucleator, or combination thereof; [0141] wherein the
polyester has an inherent viscosity of about 0.1 to about 0.35 dL/g
as measured at 25.degree. C. using 0.5 grams of polymer per 100 ml
of a solvent comprising 60 weight percent phenol and 40 weight %
tetrachloroethane, a melting temperature of about 70 to about
130.degree. C., and a heat of melting of about 0.1 cal/g to about 6
cal/g; and [0142] wherein the adhesive composition has a melt
viscosity of about 300 to about 3000 centipoise at 150.degree. C.;
[0143] II. affixing the label around the container to produce a
labeled container; [0144] III. allowing the applied hot-melt
adhesive to at least partially crystallize; and [0145] IV.
shrinking the label by exposing the labeled container to heat.
[0146] The invention may be further illustrated by the following
examples.
EXAMPLES
[0147] The inherent viscosity (IV) values were measured at
25.degree. C. in 60/40 wt/wt phenol/tetrachloroethane. Polymer
samples were dissolved in the solvent at a concentration of 0.25
g/50 mL. The viscosity of the polymer solution was determined using
a Viscotek Modified Differential Viscometer. A description of the
operating principles of the differential viscometers can be found
in ASTM Method D 5225.
[0148] Melt viscosities were measured in accordance with ASTM
Method D3236, "Apparent Viscosity of Hot Melt Adhesives and Coating
Materials," using a Brookfield DVII Viscometer equipped with a
thermosel and #27 spindle and are shown in Tables 1 and 2. The
measurement temperature was 150.degree. C. using a nominal 12 gram
sample. Melt viscosity requirements defined herein are based on the
fully formulated adhesive and therefore include the effects of
plasticizers, tackifiers, nucleators and other additives.
[0149] Melting temperature (Tm), glass transition temperature (Tg),
heat of melting (.DELTA.Hm), crystallization temperature upon
cooling (Tcc), and crystallization temperature upon heating (Tch)
were measured using Differential Scanning Calorimetry (DSC)
following ASTM Method D3418 with minor modifications, and are shown
in Tables 1 and 2. The sample weight was measured before each
measurement and was between about 2 and 5 mg. Both first and second
heating scans were performed at a scan rate of 20.degree.
C./minute. A cooling scan between the first and second heating was
also performed at this same rate in order to determine the presence
of a crystallization peak upon cooling (Tcc). Scans were typically
performed between about -50.degree. C. and 175.degree. C. to ensure
detection of Tg and all melting peaks. Data from the second cool
down and second heat are also reported in Tables 1 and 2. If the
crystallization peak upon cooling was present, then Tcc was
determined as the peak temperature of the crystallization exotherm.
Similarly, if crystallization occurred upon the 2nd heating cycle,
the value Tch was determined from the peak of this crystallization
exotherm. The melting temperature Tm was obtained from the peak
temperature of the melting endotherm of the 2nd heat cycle. If
multiple melting peaks were present, then the peak value of the
endotherm with the highest melt temperature was taken as the
melting point as set forth in the claims and Tables 1 and 2. The
absence of crystallization or melting peaks is denoted by "ND" in
the Tables.
[0150] The sum of the absolute value of the area of the melting
endotherms (one or more) was taken as the heat of melting
(.DELTA.Hm) and was used as a measure of the effective
crystallinity that forms during the heat and cool cycle. The
melting endotherm is used as a relative approximation to the amount
of crystallinity that forms in the adhesive. Values of the
endotherms are typically reported in units of cal/g or J/g.
[0151] Laboratory adhesion performance was determined by the
following procedure. Samples of each adhesive were made into
adhesive sticks, the adhesive melted, and applied with a hot melt
adhesive gun. The adhesive gun temperature was controlled to within
about 110 to 130.degree. C. to avoid shrinkage of the substrate.
Adhesive temperature was measured and controlled in the gun by
placing a thermocouple into the end of the barrel and controlling
the power input with a rheostat. Two film sample strips nominally 1
inch wide, 2 mils thick, and about 4 inches long were bonded
together in a lap shear joint using the adhesive.
[0152] A brass template was used in order to apply a controlled
width and thickness of adhesive. The template was nominally 5 mils
thick, and had a 5 mm wide strip cut out of the middle. The
template was placed over the edge of one of the film strips,
adhesive applied to an edge of the template, and then a razor blade
was used to spread the melted adhesive across the whole strip and
onto a controlled section of the film. The template was then
rapidly removed, leaving a 5 mm wide adhesive bead that was
nominally about 3 to 5 mils thick. After application, the edge of
the second film strip was placed over the adhesive bead and a joint
formed. To ensure uniform contact, a roller was run over the joint
with light pressure to ensure uniform contact between the adhesive
and the two film substrates. Total time between adhesive
application and rolling was about 2 to 4 seconds.
[0153] During adhesive application, some of the adhesives
crystallized too rapidly to permit a good bond. These were deemed
as unsatisfactory. Adhesives that applied smoothly, maintained good
tack and had good initial strength were deemed satisfactory
depending on the relative level of performance. To test adhesive
strength at shrink tunnel temperatures, both ends of the bonded
film were tacked to a wooden board to restrain the film, and the
whole structure then was placed in either a steam pot, or run
through a laboratory hot air shrink tunnel. The steam pot had a
nominal temperature of about 90 to 95.degree. C. The time to
failure, and the relative mode of failure (e.g. bond peeling,
adhesive melting) were used to assess the bond strength. The
adhesives, typically, would fail by the shrink label pulling the
adhesive bond apart, or by the adhesive melting and coming loose.
Failure times in the steam pot ranged from just a few seconds to 20
seconds or more.
[0154] While the steam pot gave a good preliminary adhesive
assessment, many of the samples were also tested using a hot air
shrink tunnel set at about 97.degree. C. (205.degree. F.). The
support board and film sample were passed through the hot air
tunnel which had a residence time of about 8 to 10 seconds. This
test gave a better comparison of bond performance to adhesive
labeling experiments that were performed on commercial scale
equipment. Both tests, as well as adhesion trial in a commercial
infrared shrink tunnel were used to evaluate overall high
temperature bond performance.
[0155] Two principle film substrates were used for almost all of
the film testing. The first was an MD stretched clear copolyester
shrink film having 50% ultimate shrinkage and a shrink force of 4
MPa. The film was made from a copolyester based on terephthalic
acid and ethylene glycol modified with 22 mole % of
cyclohexanedimethanol and 12 mole % of diethylene glycol. The
second was a microvoided shrink film also having 50% ultimate
shrinkage and 4 MPa shrink force. It was produced by MD stretching
a 75/25 blend of the above copolyester with a voiding concentrate
consisting of 50 wt % cellulose acetate, 40 wt % polypropylene and
10 wt % ethylene methyl acrylate copolymer. The microvoided film
was opaque and had a density of ca. 0.89 g/cc, making it separable
in a traditional recycle/flakewash process. Both films were
nominally 2 mils (50 microns) thick and have a shrink onset
temperature of approximately 70.degree. C. The following
abbreviations are used in Tables 1 and 2 for the various diacid and
diols monomers:
TABLE-US-00001 Diols Diacids EG = ethylene glycol T = terephthalic
acid DEG = diethylene glycol I = isophthalic acid TEG = triethylene
glycol SA = succinic acid HD = 1,6-hexanediol GA = glutaric acid BD
= 1,4-butanediol CHDA = 1,4-cyclohexane- CHDM = 1,4-cyclohexane-
dicarboxylic acid dimethanol AA = adipic acid PPG-1000 =
polypropylene DA = dimer acid 36 glycol, 1000 MW ND = none
detected
Example 1
[0156] Preparation of Polyester Hot Melt Adhesive A 500 ml round
bottom flask equipped with a ground glass head, 304 SS single blade
agitator shaft, nitrogen inlet, and a sidearm was charged with 42
grams (0.29 moles) of adipic acid, 42 grams (0.22 moles) dimethyl
terephthalate, 89 grams (0.75 moles) 1,6-hexanediol, and 0.61 ml of
a 0.98% (w/v) solution of titanium(IV) isopropoxide in n-butanol.
The flask was purged and evacuated 2 times with nitrogen before
immersion in a Belmont metal bath at 200.degree. C. where the
transesterification was allowed to proceed with evolution of
methanol under a 0.2 standard cubic feet per hour (scfm) nitrogen
sweep for 35 minutes and an additional 40 minutes at 2200 C with
agitation at 200 rpm. The recovered polymer melt was clear,
water-white and crystallized upon standing for approximately 45
minutes into opaque, white solid. An inherent viscosity of (IhV)
0.351 and a melt viscosity of 1875 cp @ 150.degree. C. were
determined. Thermal analysis yielded values of -30 C and 73 C for
the glass transition temperature and melting point, respectively,
with a heat of melting of 2.9 calories/gram. NMR analysis indicated
a final polymer comprised of 56 mole percent adipic acid residues,
44 mole percent terephthalate residues, and 100 mole percent
1,6-hexandiol residues.
Comparative Examples C1 through C21
[0157] Adhesive Testing with Neat Adhesive Samples--Comparative
examples C1 through C21 were prepared using the same procedure as
described above for Example 1. These polyesters did not provide
satisfactory adhesion performance for a variety of reasons. These
comparative samples were quantified using DSC, melt viscosity
testing and the results are shown in Table 1. In the summary, the
mole percentages of the diacid and diol components are shown and
are based on 100 mole % total of acids, and 100 mole % total of
diols. Viscosities are given in units of centipoise, inherent
viscosities are in units of dl/g, and temperatures are in units of
degrees Celsius. The melt viscosities for Comparative Examples
C1-C7 were not measured and are indicated as not available ("n/a")
in Table 1.
[0158] Adhesion testing was performed, where possible, via hot melt
adhesive gun testing. The comparative examples were difficult to
bond, showed poor bond strength under shrink testing, were too
viscous, and/or had a melting temperature that was too high.
Samples listed as "poor" in Tables I and II performed inadequately,
and would not be acceptable for any type of RAS or general adhesive
application. Samples listed as "fair" exhibited better viscosity,
melting temperature, and bond strength properties, but were not
judged to be functional adhesives. In contrast, adhesives listed as
"excellent" are expected to perform well in RAS applications
whereas samples listed as "good" are expected to perform well as
general purpose adhesives and for general RAS applications with
films having low shrinkage or lower shrink onset temperatures
[0159] With regards to specific reasons for failure, Comparative
Examples C1 and C2 were poor performers because they crystallized
too quickly to process into strong adhesive bonds. The adhesive
formed unacceptably brittle bonds in the few instances where a bond
could be formed.
[0160] Other Comparative Examples, such as C8, and C9 applied well,
but showed no discernible crystallinity, had low melt strength
during shrinkage testing, and the adhesive bond failed in the
shrink tunnel. In contrast, Comparative Examples C10 through C15
had excessively high melt viscosities (>3000 cP at 150.degree.
C.) and could not sufficiently softened to enable uniform
application. Comparative Example C18 bonded well but did not have
sufficient thermal resistance and the bond failed quickly under
heat. Comparative Example C19 could not be sufficiently melted at a
cool enough temperature, and tended to curl the shrink film when
applied.
TABLE-US-00002 TABLE I Comparative Data for Neat Samples Acids
Glycols IV Visc. Tg Tcc Tch Tm .DELTA.Hm Bond Ex (mole %) (mole %)
(dL/g) (cP) (.degree. C.) (.degree. C.) (.degree. C.) (.degree. C.)
(cal/g) Quality C1 SA (100) BD (100) 1.44 n/a 66 69 98 115 13.5
poor C2 SA (100) HD (100) 1.25 n/a ND 17 ND 62 13.1 poor C3 AA
(100) EG (100) 0.83 n/a -42 13 18 49 8.7 poor C4 AA (100) BD (100)
0.96 n/a ND 25 ND 62 15.7 poor C5 SA (100) BD (100) 0.51 n/a 19 63
86 116 15.7 poor C6 SA (100) BD (90)/EG (10) 1.43 n/a ND 59 94 114
14.5 poor C7 SA (75)/AA (25) BD (100) 1.10 n/a -44 24 -6 89 10.9
poor C8 CHDA (100) DEG (80)/CHDM (20) 0.28 2170 -3 ND ND ND ND poor
C9 CHDA (100) DEG (60)/CHDM (40) 0.36 14800 5 ND ND ND ND poor C10
AA (100) CHDM (80)/DEG (20) 0.66 46200 -34 ND 36 70 2.5 poor C11
CHDA (100) DEG (60)/CHDM (40) 0.34 8437 4 ND ND ND ND poor C12 CHDA
(100) DEG (70)/CHDM (30) 0.38 12570 -1 ND ND ND ND poor C13 T (100)
HD (80)/BD (20) 0.40 33930 15 78 ND 126 9.2 poor C14 AA (100) CHDM
(60)/DEG (40) 0.59 13070 -39 ND ND ND ND poor C15 GA (100) CHDM
(80)/DEG (20) 0.47 10800 -32 ND ND ND ND poor C16 CHDA (100) DEG
(60)/CHDM (40) 0.31 2755 -6 ND ND ND ND fair C17 CHDA (100) DEG
(80)/CHDM (20) 0.40 10100 -2 ND ND ND ND poor C18 AA (50)/CHDA (50)
DEG (60)/CHDM (40) 0.37 3440 -26 ND ND ND ND fair C19 AA (50)/T
(50) BD (100) 0.29 2097 -37 87 ND 135 5.6 poor C20 AA (50)/T (40)/I
(10) BD (100) 0.27 1217 -38 33 ND 95 6.3 fair C21 AA (45)/T (45)/GA
(10) BD (100) 0.27 1050 -41 65 ND 113 6.2 fair
Examples 1 Through 15
[0161] Adhesive Testing with Neat Adhesives--Examples 1-15 are neat
polyester adhesives that were prepared using the same procedure as
described above for Example 1. Their thermal and performance
properties are shown in Table 2. All of these samples are neat and
therefore do not contain any plasticizers or modifiers. As with the
Comparative Examples described above, the samples were applied to
polyester film strips using an adhesive gun and a template. Sample
performance during application and subsequent shrink tunnel testing
was assessed.
[0162] In general, all of the Examples in Table 2 were capable of
producing a good bond that would survive the shrink tunnel.
Examples 1 and 15, for example, produced excellent bonds but had a
lower melt temperature. This adhesive would be useful for general
adhesive applications and for RAS applications with lower shrink
onset temperatures
TABLE-US-00003 TABLE 2 Data for Neat Samples Acids Glycols IV Visc.
Tg Tcc Tch Tm .DELTA.Hm Bond Ex (mole %) (mole %) (dL/g) (cP)
(.degree. C.) (.degree. C.) (.degree. C.) (.degree. C.) (cal/g)
Quality 1 AA (56)/T (44) HD (100) 0.35 1875 3 45 ND 73 2.9 good 2
AA (57)/T (43) BD (100) 0.30 1277 -41 62 ND 111 4.5 good 3 AA
(55)/T (45) BD (100) 0.33 1977 -45 58 ND 105 3.2 excellent 4 AA
(57)/T (43) BD (90)/CHDM (10) 0.31 1875 0 ND ND 99 4.5 good 5 GA
(57)/T (43) BD (100) 0.32 2305 -39 55 ND 120 5.3 good 6 AA (55)/T
(35)/I (10) BD (100) 0.34 2200 -35 25 10 85 4.0 good 7 AA (45)/T
(45)/I (10) BD (100) 0.30 2207 -29 49 ND 116 5.4 good 8 AA (35)/T
(45)/I (20) BD (100) 0.29 1695 -26 ND 29 87 3.3 excellent 9 AA
(40)/T (40)/I (20) BD (100) 0.28 1865 -25 33 22 99 5.5 good 10 AA
(55)/T (40)/I (5) BD (100) 0.32 1705 -41 50 60 107 3.4 excellent 11
AA (45)/T (45)/GA (10) BD (100) 0.30 1595 -40 67 ND 117 4.8 good 12
AA (45)/T (45)/I (10) BD (90)/CHDM (10) 0.28 1255 -40 52 ND 115 4.3
good 13 AA (45)/T (45)/I (10) BD (90)/DEG (10) 0.32 1947 -38 33 ND
104 5.9 good 14 AA (50)/T (35)/I (15) BD (100) 0.27 1135 -35 ND 15
84 5.3 good 15 AA (50)/T (30)/I (20) BD (100) 0.31 1855 -32 ND 33
72 2.0 good
[0163] The remaining Examples in Table 2 showed "good" bond quality
and produced acceptable bonds, but with less toughness and tack in
comparison with the Examples in Table 2 labeled as having
"excellent" bond quality. Many of these had intermediate
crystallization levels that rendered them partially tacky. These
samples were found in other experiments to benefit most from the
inclusion of crystallization-reducing plasticizers and waxes.
* * * * *